Superlative Porous Organic Polymers for Photochemical and Electrochemical CO2 Reduction Applications: From Synthesis to Functionality.

To mimic the carbon cycle at a kinetically rapid pace, the sustainable conversion of omnipresent CO2 to value-added chemical feedstock and hydrocarbon fuels implies a remarkable prototype for utilizing released CO2. Porous organic polymers (POPs) have been recognized as remarkable catalytic systems for achieving large-scale applicability in energy-driven processes. POPs offer mesoporous characteristics, higher surface area, and superior optoelectronic properties that lead to their relatively advanced activity and selectivity for CO2 conversion. In comparison to the metal organic frameworks, POPs exhibit an enhanced tendency toward membrane formation, which governs their excellent stability with regard to remarkable ultrathinness and tailored pore channels. The structural ascendancy of POPs can be effectively utilized to develop cost-effective catalytic supports for energy conversion processes to leapfrog over conventional noble metal catalysts that have nonlinear techno-economic equilibrium. Herein, we precisely surveyed the functionality of POPs from scratch, classified it, and provided a critical commentary of its current methodological advancements and photo/electrochemical achievements in the CO2 reduction reaction.

MBenes for Energy Conversion: Advances, Bottlenecks, and Prospects.

The advent of two-dimensional layered materials has bolstered the development of catalytic endeavors for energy conversion and storage. MXenes (transition metal carbides/nitrides) have already consolidated their candidature in the past decade due to their enhanced compositional and structural tunabilities through surface modifications. Perseverant research in engineering MXene based materials has led to the inception of MBenes (transition metal borides) as promising catalytic systems for energy-driven operations. Physicochemical superiorities of MBenes such as escalated conductivity and hydrophilicity, unique surface and geometrical domains, and higher stability and modulus of elasticity provide the reaction-friendly milieu to exploit these materials. Nevertheless, the research on MBenes is embryonic and requires the thorough realization of their scientific significance. Herein, we aim to discuss the advancements, challenges, and outlooks of MBenes with respect to their energy conversion HER, CO2RR, and NRR applications.

Enhanced Photo/Electrocatalytic Hydrogen Evolution by Hydrothermally Derived Cu-Doped TiO2 Solid Solution Nanostructures.

Highly efficient nanocatalysts with a high specific surface area were successfully synthesized by a cost-effective and environmentally friendly hydrothermal method. Structural and elemental purity, size, morphology, specific surface area, and band gap of pristine and 1 to 5% Cu-doped TiO2 nanoparticles were characterized by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), energy dispersive X-ray analysis (EDAX), inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography-high resolution mass spectrometry (LC-HRMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area, Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible diffused reflectance spectroscopy (UV-DRS) studies. The XPS and EPR findings indicated the successful integration of Cu ions into the TiO2 lattice. UV-DRS and BET surface area investigations revealed that with an increase in dopant concentration, Cu-doped TiO2 NPs show a decrease in band gap (3.19-3.08 eV) and an increase in specific surface area (169.9-188.2 m2/g). Among all compositions, 2.5% Cu-doped TiO2 has shown significant H2 evolution with an apparent quantum yield of 17.67%. Furthermore, the electrochemical water-splitting study shows that 5% Cu-doped TiO2 NPs have superiority over pristine TiO2 for H2 evolution reaction. It was thus revealed that the band gap tuning with the desired dopant concentration led to enhanced photo/electrocatalytic sustainable energy applications.

Photo/electro catalytic green hydrogen production promoted by Ga modified Co0.6Cu0.4Fe2O4 nano catalysts.

The current work concentrates on the fabrication of Ga doped Co0.6Cu0.4Fe2O4 nanocatalysts via sol-gel auto-combustion (SGA) for the production of green and sustainable source of energy i.e., hydrogen through photocatalytic and electrocatalytic routes. Single-phased cubic crystal structure with Fd3m geometry was observed through XRD patterns. FESEM images show the aggregated and spherical shaped grains with distinct grain boundaries and average grain size of 1.04 and 1.39 µm for the Co0.6Cu0.4Fe2O4, and Co0.6Cu0.4Ga0.02Fe1.98O4 nanomaterials. Soft magnetic behaviour with a coercivity (Hc) and saturation magnetization (Ms) of 235.32-357.26 Oe and 54.65-61.11 emu/g was obtained for the produced nanomaterials. The estimation of photocatalytic nature for generating H2 was conducted using the sacrificial agents i.e., 0.128 M Na2S and 0.079 M Na2SO3. The analysis focused on measuring the maximum H2 generation was achieved by photocatalysts throughout three consecutive 4-h cycles. Out of all compositions, Co0.6Cu0.4Ga0.02Fe1.98O4 nanomaterial have the highest photocatalytic activity of 16.71 mmol gcat-1. However, the electrocatalytic behaviour of prepared Co0.6Cu0.4GaxFe2-xO4 (x = 0.00-0.03) electrocatalysts were determined for HER (Hydrogen evolution reaction) reaction. The overpotential values of Co0.6Cu0.4Fe2O4, Co0.6Cu0.4Ga0.01Fe1.99O4, Co0.6Cu0.4Ga0.02Fe1.98O4, and Co0.6Cu0.4Ga0.03Fe1.97O4 catalysts at 10 mA cm-2 were -0.81, -0.85, -1.03, and 1.21 V, correspondingly. Thus, at cathode current density of 10 mA/cm-2, an elevation in overpotential was noted, which indicates that the undoped Co0.6Cu0.4Fe2O4 (x = 0.00) electrocatalyst have remarkable electrocatalytic HER activity. Consequently, owing to photo/electro catalytic water splitting traits, the prepared catalysts are highly efficient for the green hydrogen generation.

Decorating Thermodynamically Stable (101) Facets of TiO2 with MoO3 for Multifunctional Sustainable Hydrogen Energy and Ammonia Gas Sensing Applications.

The simultaneous realization of sustainable energy and gas sensors dealing with the emission of pollutants is indispensable as the former thrives on the minimization of the latter. However, there is a dearth of multifunctional nanocatalysts in the literature. This ascertains the importance of multifunctional semiconductors which can be utilized in H2 generation via overall water splitting and in the gas sensing of global pollutants such as NH3. MoO3-decorated TiO2 Z-scheme heterostructures exceptionally escalate the photochemical and photo/electrochemical H2 evolution performance and gas sensing response of TiO2 owing to the synergistic relationship between TiO2 and MoO3. Extensive structural, morphological, and optical characterizations, theoretical studies, and XPS results were exploited to develop a mechanistic framework of photochemical H2 evolution. The photochemical response of the optimum TiO2-MoO3 composition (20 wt % MoO3-TiO2) was found to be nearly 12- and 20-fold superior to the pristine TiO2 and MoO3 photocatalysts, respectively, with the remarkable H2 evolution rate of 9.18 mmol/g/h and AQY of 36.02%. In addition, 20 wt % MoO3-TiO2 also showed advanced photo/electrochemical efficiency with 0.61/0.7 V overpotential values toward HER due to the higher electrochemically active surface area and Tafel slope as low as 65 mV/dec. The gas sensing response of 20 wt % MoO3-TiO2 toward NH3 gas turned out to be 2.5-fold higher than that of the pristine TiO2 gas sensor.

Photo/electrocatalytic hydrogen evolution using Type-II Cu2O/g-C3N4 Heterostructure: Density functional theory addresses the improved charge transport efficiency.

One of the most efficient ways for the photogenerated charge carriers is by the development of heterojunction between p-type and n-type semiconductors, which creates an interfacial charge transfer between two semiconductors. By enhancing the bifunctional characteristics for hydrogen generation via photocatalytic and electrocatalytic water splitting reaction, we report the type-II Cu2O/g-C3N4 heterostructure in this article. Due to significantly increased catalytically active sites for the hydrogen evolution reaction (HER) reaction during electrocatalysis and decreased charge transfer resistance, the as-prepared heterostructure exhibits a lower overpotential of 47 and 72 mVdec-1 for the HER and oxygen evolution reactions (OER), respectively, when compared to alone g-C3N4. In addition, Cu2O/g-C3N4 heterostructures have a higher photocatalytic hydrogen evolution of 3492 µmol gcat-1 in the presence of Triethanolamine as a sacrificial agent, which is nearly 2-fold times greater than g-C3N4 (1818 µmol gcat-1) after 5 h of continuous light-irradiation. Moreover, produced heterostructure exhibits 81% of Faradaic efficiency and 18% of apparent quantum yield. This work successfully explains how the rise in water splitting is induced by the transfer of photogenerated electrons in a cascade way from p-type Cu2O to the n-type g-C3N4 using density functional theory (DFT) calculations.

Symbiotic MoO3-SrTiO3 Heterostructured Nanocatalysts for Sustainable Hydrogen Energy: Combined Experimental and Theoretical Simulations.

Highly efficient Z-scheme MoO3-SrTiO3 heterostructured nanocatalytic systems were engineered via a sol-gel chemical route and exploited in green H2 energy synthesis via overall water splitting. The optical and electronic investigations corroborated the enhancement of the optoelectronic properties of SrTiO3 after the incorporation of MoO3. Emergence of the interfacial charge transfer between SrTiO3 and MoO3 is the driving force, which synergistically triggered the catalytic efficiency of MoO3-SrTiO3 heterostructures. The substitution of Ti4+ by Mo6+ ions led to the suppression of Ti3+ mid-gap states, as the potential involved in the Mo6+/Mo5+ reduction is higher than that in Ti4+/Ti3+. Theoretical studies were employed in order to comprehend the mechanism behind the advancement in the catalytic activity of MoO3-SrTiO3 porous heterostructures, which also possessed a higher surface area. 2% MoO3-SrTiO3 exhibited the optimum catalytic response toward H2 evolution via photochemical, electrochemical, and photo-electrochemical water splitting. 2% MoO3-SrTiO3 evolved H2 at the fourfold higher rate than SrTiO3 with phenomenal 16.06% AQY during photochemical water splitting and photo-degraded MB dye at nearly 88% against the 42% degradation in SrTiO3-led photocatalysis. Electrochemical and photo-electrochemical investigations also manifested the superiority of 2% MoO3-SrTiO3 toward HER, as it exhibited accelerated current and photocurrent densities of 25.02 and 27.45 mA/cm2, respectively, at the 1 V potential. EIS studies demonstrated the improved charge separation efficiency of MoO3-SrTiO3 heterostructures. This work highlights the multi-dimensional approach of obtaining green H2 energy as the sustainable energy source using MoO3@SrTiO3 heterostructures.

Ag-Doped WO3 Nanoplates as Heterogenous Multifunctional Catalyst for Glycerol Acetylation, Electrocatalytic and Enhanced Photocatalytic Hydrogen Production.

Herein, we report a hydrothermal method to synthesize pristine and Ag-doped WO3 nanoplates and study their multifunctional competence in the accomplishment of enhanced catalytic organic conversion and highly efficient photocatalytic and electrocatalytic H2 evolution reactions. The as-synthesized nanoplates were characterized by using various techniques including X-ray diffraction, field emission scanning electron microscopy-energy-dispersive X-ray analysis, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and BET surface area studies. The significant catalytic performance was shown by 1% Ag-doped WO3 nanoplates with 100% glycerol conversion and 90% triacetin selectivity. The photocatalytic activity was also examined toward water splitting H2 evolution reaction which demonstrates the highest H2 evolution of 12.06 mmol g-1 catalyst for 1% Ag-doped WO3 nanoplates in a time span of 8 h. Moreover, the electrocatalytic hydrogen evolution reaction was also monitored in acidic media (0.1 M H2SO4) which demonstrates good results for 1% Ag-doped WO3 nanoplates with a low overpotential of 0.53 V and a low Tafel slope of 40 mV dec-1.

Magnetically recoverable sol-gel auto-combustion developed Ni1-xCuxDyyFe2-yO4 magnetic nanoparticles for photocatalytic, electrocatalytic, and antibacterial applications.

Copper and dysprosium doped NiFe2O4 magnetic nanomaterials, Ni1-xCuxDyyFe2-yO4 (x = y = 0.00, 0.01, 0.02, 0.03), was prepared by utilizing sol-gel auto-combustion approach to inspect the photodegradation of methylene blue (MB) pollutant and also, to perform the electrocatalytic water splitting and antibacterial studies. The XRD analysis reveal the growth of a single-phase spinel cubic structure for produced nanomaterials. The magnetic traits show an increasing trend in saturation magnetization (Ms) from 40.71 to 47.90 emu/g along with a decreasing behaviour of coercivity from 158.09 to 156.34 Oe at lower and higher Cu and Dy doping content (x = 0.0-0.01). The study of optical band gap values of copper and dysprosium-doped nickel nanomaterials decreased from 1.71 to 1.52 eV. This will increase the photocatalytic degradation of methylene blue pollutant from 88.57% to 93.67% under natural sunlight, respectively. These findings clearly show that under natural sunlight irradiation for 60 min, the produced N4 photocatalyst displays the greatest photocatalytic activity with a maximum removal percentage of 93.67%. The electrocatalytic characteristics of produced magnetic nanomaterials for both HER and OER were examined with a Calomel electrode taking as a reference in a 0.5 N H2SO4 and 0.1 N KOH electrolyte. The N4 electrode demonstrated considerable 10 and 0.024 mA/cm2 of current density, with onset potentials of 0.99 and 1.5 V for HER and OER and also, have tafel slopes of 58.04 and 295 mV/dec, respectively. The antibacterial activity for produced magnetic nanomaterials was examined against various bacteria (Bacillus subtilis, Staphylococcus aureus, S. typhi, and P. aeruginosa) in which N3 sample produced significant inhibition zone against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) but no zone of inhibition against gram-negative bacteria (S. typhi and P. aeruginosa). With all these superior traits, the produced magnetic nanomaterials are highly valuable for the wastewater remediation, hydrogen evolution, and biological applications.

Regulated electrochemical performance of manganese oxide cathode for potassium-ion batteries: A combined experimental and first-principles density functional theory (DFT) investigation.

Potassium-ion batteries (KIBs) are promising energy storage devices owing to their low cost, environmental-friendly, and excellent K+ diffusion properties as a consequence of the small Stoke's radius. The evaluation of cathode materials for KIBs, which are perhaps the most favorable substitutes to lithium-ion batteries, is of exceptional importance. Manganese dioxide (α-MnO2) is distinguished by its tunnel structures and plenty of electroactive sites, which can host cations without causing fundamental structural breakdown. As a result of the satisfactory redox kinetics and diffusion pathways of K+ in the structure, α-MnO2 nanorods cathode prepared through hydrothermal method, reversibly stores K+ at a fast rate with a high capacity and stability. It has a first discharge capacity of 142 mAh/g at C/20, excellent rate execution up to 5C, and a long cycling performance with a demonstration of moderate capacity retention up to 100 cycles. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) simulations confirm that the K+ intercalation/deintercalation occurs through 0.46 K movement between MnIV/MnIII redox pairs. First-principles density functional theory (DFT) calculations predict a diffusion barrier of 0.31 eV for K+ through the 1D tunnel of α-MnO2 electrode, which is low enough to promote faster electrochemical kinetics. The nanorod structure of α-MnO2 facilitates electron conductive connection and provides a strong electrode-electrolyte interface for the cathode, resulting in a very consistent and prevalent execution cathode material for KIBs.

Metal-Organic Precursor Synthesis, Structural Characterization, and Multiferroic Properties of GdFeO3 Nanoparticles.

GdFeO3 nanoparticles were fabricated by a facile metal-organic precursor method using citric acid as a complexing agent. The phase purity and structural analysis by powder X-ray diffraction and FTIR studies indicates that the material is highly crystalline with an orthorhombic structure. Electron microscopic (TEM and SEM) studies of rare earth ferrites reveal worm-shaped nanoparticles with an average grain size of 95 nm. The high-resolution TEM study provides an insightful image, which shows an interplanar spacing of approximately 0.12 nm that corresponds to the (112) crystalline plane. A high surface area of 231.5 m2 g-1 has been achieved with a mesoporous texture, which in turn gives a high dielectric constant. Well-defined hysteresis is obtained with a saturation magnetization of 17.5 emu g-1, remanent magnetization of 3.9 emu g-1, and coercive field of -446 Oe. Room-temperature ferroelectricity in GdFeO3 nanoparticles has been found for the first time with no leaky current and hence may be used in multistate memory devices.

Tin Oxide Based Hybrid Nanostructures for Efficient Gas Sensing.

Tin oxide as a semiconductor metal oxide has revealed great potential in the field of gas sensing due to its porous structure and reduced size. Especially for tin oxide and its composites, inherent properties such as high surface areas and their unique semiconducting properties with tunable band gaps make them compelling for sensing applications. In combination with the general benefits of metal oxide nanomaterials, the incorporation of metal oxides into metal oxide nanoparticles is a new approach that has dramatically improved the sensing performance of these materials due to the synergistic effects. This review aims to comprehend the sensing mechanisms and the synergistic effects of tin oxide and its composites in achieving high selectivity, high sensitivity and rapid response speed which will be addressed with a full summary. The review further vehemently highlights the advances in tin oxide and its composites in the gas sensing field. Further, the structural components, structural features and surface chemistry involved in the gas sensing are also explained. In addition, this review discusses the SnO2 metal oxide and its composites and unravels the complications in achieving high selectivity, high sensitivity and rapid response speed. The review begins with the gas sensing mechanisms, which are followed by the synthesis methods. Further key results and discussions of previous studies on tin metal oxide and its composites are also discussed. Moreover, achievements in recent research on tin oxide and its composites for sensor applications are then comprehensively compiled. Finally, the challenges and scope for future developments are discussed.

Type-II CuFe2O4/Graphitic Carbon Nitride Heterojunctions for High-Efficiency Photocatalytic and Electrocatalytic Hydrogen Generation.

Solar water splitting has emerged as an urgent imperative as hydrogen emerges as an increasingly important form of energy storage. g-C3N4 is an ideal candidate for photocatalytic water splitting as a result of the excellent alignment of its band edges with water redox potentials. To mitigate electron-hole recombination that has limited the performance of g-C3N4, we have developed a semiconductor heterostructure of g-C3N4 with CuFe2O4 nanoparticles (NPs) as a highly efficient photocatalyst. Visible-light-driven photocatalytic properties of CuFe2O4/g-C3N4 heterostructures with different CuFe2O4 loadings have been examined with two sacrificial agents. An up to 2.5-fold enhancement in catalytic efficiency is observed for CuFe2O4/g-C3N4 heterostructures over g-C3N4 nanosheets alone with the apparent quantum yield of H2 production approaching 25%. The improved photocatalytic activity of the heterostructures suggests that introducing CuFe2O4 NPs provides more active sites and reduces electron-hole recombination. The g-C3N4/CuFe2O4 heterostructures furthermore show enhanced electrocatalytic HER activity as compared to the individual components as a result of which by making heterostructures g-C3N4 with CuFe2O4 increased the active catalytic surface for the electrocatalytic water splitting reaction. The enhanced faradaic efficiency of the prepared heterostructures makes it a potential candidate for efficient hydrogen generation. Nevertheless, the designed heterostructure materials exhibited significant photo- and electrocatalytic activity toward the HER, which demonstrates a method for methodically enhancing catalytic performance by creating heterostructures with the best energetic offsets.

Self-Assembled Interwoven Nanohierarchitectures of NaNbO3 and NaNb1-x Ta x O3 (0.05 ≤ x ≤ 0.20): Synthesis, Structural Characterization, Photocatalytic Applications, and Dielectric Properties.

Dependence on fossil fuels for energy purposes leads to the global energy crises due to the nonrenewable nature and high CO2 production for environmental pollution. Therefore, new ways of nanocatalysis for environmental remediation and sustainable energy resources are being explored. Herein, we report a facile surfactant free, low temperature, and environmentally benign hydrothermal route for development of pure and (5, 10, 15, and 20 mol %) Ta-doped horizontally and vertically interwoven NaNbO3 nanohierarchitecture photocatalysts. To the best of our knowledge, such a type of hierarchical structure of NaNbO3 has never been reported before, and changes in the microstructure of these nanoarchitectures on Ta-doping has also been examined for the first time. As-synthesized nanostructures were characterized by different techniques including X-ray diffraction analysis, electron microscopic studies, X-ray photoelectron spectroscopic studies, etc. Ta-doping considerably affects the microstructure of the nanohierarchitectures of NaNbO3, which was analyzed by FESEM analysis. The UV-visible diffused reflectance spectroscopy study shows considerable change in the band gap of as-synthesized nanostructures and was found to be ranging from 2.8 to 3.5 eV in pure and different mole % Ta-doped NaNbO3. With an increase in dopant concentration, the surface area increases and was equal to 5.8, 6.8, 7.0, 9.2, and 9.7 m2/g for pure and 5, 10, 15, and 20 mol % Ta-doped NaNbO3, respectively. Photocatalytic activity toward the degradation of methylene blue dye and H2 evolution reaction shows the highest activity (89% dye removal and 21.4 mmol g-1 catalyst H2 evolution) for the 10 mol % NaNbO3 nanostructure which was attributed to a change in the conduction band maximum of the material. At 100 °C and 500 kHz, the dielectric constants of pure and 5, 10, 15, and 20 mol % Ta-doped NaNbO3 were found to be 111, 510, 491, 488, and 187, respectively. The current study provides the rational insight into the design of nanohierarchitectures and how microstructure affects different properties of the material upon doping.

Chemical fabrication, structural characterization and photocatalytic water splitting application of Sr-doped SnO2nanoparticles.

Semiconductor photocatalysis has gained considerable attention in recent years due to their enabling nature to convert solar energy into fuels of renewable hydrocarbon. However, many of them suffer from some drawbacks like the inability to visible light irradiation and wide band gaps. Herein, we have synthesized monophasic strontium (Sr) doped SnO2nanoparticles by a cost-effective and environmental friendly hydrothermal method. As-synthesized nanoparticles showed rutile crystalline structure with irregular and rough cubical shape and no other elemental impurities. Sr-doped SnO2nanoparticles show a constant decrease in bandgap with increasing dopant concentration, which is estimated for excellent photocatalytic activity. The photocatalytic water splitting of as-prepared Sr-doped SnO2nanoparticles for H2generation shows a large influence of the increasing dopant concentration related to the narrowing bandgap on H2generation rate. Hence, the tunable bandgap with adjusted dopant concentration indicates that band gap tuning through doping for produced nanostructures may open up a new opportunities for photocatalytic and other optoelectronic applications.

Modified, Solvothermally Derived Cr-doped SnO2 Nanostructures for Enhanced Photocatalytic and Electrochemical Water-Splitting Applications.

Cr-doped SnO2 nanostructures with a dopant concentration ranging from 1 to 5% have been successfully prepared using low-temperature modified solvothermal synthesis. The as-prepared nanoparticles showed a rutile tetragonal structure with a rough undefined morphology having no other elemental impurities. The particle shape and size, band gap, and specific surface area of the samples were investigated by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, UV-visible diffused reflectance spectroscopy, and Brunauer-Emmett-Teller surface area studies. The optical band gap was found in the range of 3.23-3.67 eV and the specific surface area was in the range of 108-225 m2/g, which contributes to the significantly enhanced photocatalytic and electrochemical performance. Photocatalytic H2 generation of as-prepared Cr-doped SnO2 nanostructures showed improved effect of the increasing dopant concentration with narrowing of the band gap. Electrochemical water-splitting studies also stressed upon the superiority of Cr-doped SnO2 nanostructures over pristine SnO2 toward hydrogen evolution reaction and oxygen evolution reaction responses.

Rare earth doped metal oxide nanoparticles for photocatalysis: a perspective.

Metal oxides are well-known materials that have been considered as the prominent photocatalysts. Photocatalysis is a promising way to address the environmental issues which are caused by fossil fuel the combustion and industrial pollutants. Lot of efforts such as doping of metal oxides with metals, non-metals have been made to enhance their photocatalytic activity. More specifically, in this review we have discussed detailed synthesis procedures of rare earth doped metal oxides performed in the past decades. The advantage of doping metal oxides with rare earth metals is that they readily combine with functional groups due to the 4f vacant orbitals. Moreover, doping rare earth metals causes absorbance shift to the visible region of the electromagnetic spectrum which results to show prominent photocatalysis in this region. The effect of rare earth doping on different parameters of metal oxides such as band gap and charge carrier recombination rate has been made in great details. In perspective section, we have given a brief description about how researchers can improve the photocatalytic efficiencies of different metal oxides in coming future. The strategies and outcomes outlined in this review are expected to stimulate the search for a whole new set of rare earth doped metal oxides for efficient photocatalytic applications.

Recent advances in anticancer and antimicrobial activity of silver nanoparticles synthesized using phytochemicals and organic polymers.

Development of eco-friendly synthetic methods has resulted in the production of biocompatible Ag NPs for applications in medical sector. To overcome the prevailing antibiotic resistance in bacteria, Ag NPs are being extensively researched over the past few years due to their broad spectrum and robust antimicrobial properties. Silver nanoparticles are also being studied widely in advanced anticancer therapy as an alternative anticancer agent to combat cancer in an effective manner. Keeping this backdrop in consideration, this review aims to provide an extensive coverage of the recent progresses in the green synthesis of Ag NPs specifically using plant derived reducing agents such phytochemicals and numerous other biopolymers. Current development in antimicrobial activity of Ag NPs against various pathogens has been deliberated at length. Recent advances in potent anticancer activity of the biogenic Ag NPs against various cancerous cell lines has also been discussed in detail. Mechanistic details of the synthesis of Ag NPs, their anticancer and antimicrobial action has also been highlighted.

Gold Nanoparticles as Efficient Catalysts in Organic Transformations.

This review summarizes the utilization of gold nanoparticles as efficient catalysts for a variety of chemical transformations like oxidation, hydrogenation, and coupling reactions as compared to conventional catalytic materials. This review explores the gold nanoparticles-based catalysts for the liquid phase chemo-selective organic transformations which are proving to be evergreen reactions and have importance for industrial applications. Apart from organic transformation reactions, gold nanoparticles have been found to be applicable in removing the atmospheric contaminants and improving the efficiency of the fuel cells by removing the impurities of carbon monoxide.

Multifunctional Efficacy of Environmentally Benign Silver Nanospheres for Organic Transformation, Photocatalysis, and Water Remediation.

Highly crystalline and monophasic silver nanospheres with a high specific surface area of 57 m2/g have been synthesized by an environmentally benign rapid chemical reduction using l-alanine for catalytic transformation, photocatalytic degradation, and bacterial disinfection, which can provide an ample strategy for water remediation. Electron microscopic analysis confirms the spherical morphology of as-prepared silver nanoparticles with an average grain size of 20 nm. Silver nanospheres showed excellent catalytic activity for the catalytic hydrogenation and conversion (95.6%) of 4-nitrophenol to 4-aminophenol. Significant photocatalytic degradation proficiency was also shown for methylene blue (94.5%) and rhodamine B (96.3%) dyes under solar irradiation. The antibacterial behavior of Ala-Ag nanospheres was demonstrated through the disk diffusion antibacterial assay against Gram-positive (Escherichia coli) and Gram-negative (Staphylococcus aureus) bacteria. Multifunctional efficiency of as-prepared Ala-Ag nanospheres for water remediation has also been established.