Phosphorus-Doped Nickel Oxide Micro-Supercapacitor: Unleashing the Power of Energy Storage for Miniaturized Electronic Devices.

For an uninterrupted self-powered network, the requirement of miniaturized energy storage device is of utmost importance. This study explores the potential utilization of phosphorus-doped nickel oxide (P-NiO) to design highly efficient durable micro-supercapacitors. The introduction of P as a dopant serves to enhance the electrical conductivity of bare NiO, leading to 11-fold augmentation in volumetric capacitance to 841.92 Fcm-3 followed by significant enhancement of energy and power density from 6.71 to 42.096 mWhcm-3 and 0.47 to 1.046 Wcm-3, respectively. Theoretical calculations used to determine the adsorption energy of OH- ions, revealing higher in case of bare NiO (1.52 eV) as compared to phosphorus-doped NiO (0.64 eV) leading to high electrochemical energy storage performance. The as-designed micro-supercapacitor (MSC) device demonstrates a facile integration with the photovoltaic system for renewable energy storage and smooth transfer to external loads for enlightening the blue LED for ≈1 min. The choice of P-NiO/Ni not only contributes to cost reduction but also ensures minimal lattice mismatch at the interface facilitating high durability up to 15 K cycles along with capacitive retention of ≈100% and coulombic efficiency of 93%. Thus, the heterostructure unveils the possibilities of exploring miniaturized energy storage devices for portable electronics.

Porous Carbon Template Decorated with MOF-Driven Bimetallic Phosphide: A Suitable Heterostructure for the Production of Uninterrupted Green Hydrogen via Renewable Energy Storage Device.

Water splitting via an uninterrupted electrochemical process through hybrid energy storage devices generating continuous hydrogen is cost-effective and green approach to address the looming energy and environmental crisis toward constant supply of hydrogen fuel in fuel cell driven automobile sector. The high surface area metal-organic framework (MOF) driven bimetallic phosphides (ZnP2 @CoP) on top of CNT-carbon cloth matrix is utilized as positive and negative electrodes in energy storage devices and overall water splitting. The as-prepared positive electrode exhibits excellent specific capacitances/capacity of 1600 F g-1 /800 C g-1 @ 1A g-1 and the corresponding hybrid device reveals an energy density of 83.03 Wh kg-1 at power density of 749.9 W kg-1 . Simultaneously, the electrocatalytic performance of heterostructure shows overpotentials of 90 mV@HER and 204 mV@OER at current density of 10 and 20 mA cm-2 , respectively in alkaline electrocatalyzer. Undoubtedly, it shows overall water splitting with low cell voltage of 1.53 V@10 mA cm-2 having faradic and solar-to-hydrogen conversion efficiency of 98.81% and 9.94%, respectively. In addition, the real phase demonstration of the overall water-splitting is performed where the electrocatalyzer is connected with a series of hybrid supercapacitor devices powered up by the 6 V standard silicon solar panel to produce uninterrupted green H2 .

Utilizing Strain-Engineered Stable Halide Perovskite for Interfacial Interaction with Molecular Dipoles To Enhance Ferroelectric Switching and Piezoresponse in Polymer Composite Nanofibers.

Mechanical and solar to electrical energy conversion using piezo- and ferroelectric and photovoltaic effects may be a practical answer to the rising energy demand. In this quest, piezoelectric polymer poly(vinylidene fluoride-hexafluoroproylene) (P(VDF-HFP)) has gained interest due to its superior piezo- and ferroelectricity. In photovoltaic applications, inorganic halide perovskite (IHP) of CsPbI3 is considered a prime model compound. However, its application is limited because of the photoactive perovskite phase instability at ambient conditions. Here, we report the in situ synthesis of the stable perovskite γ-CsPbI3 through an electrospinning process at room temperature, encapsulated within a ferroelectric copolymer poly(vinylidene fluoride-hexafluoroproylene) (P(VDF-HFP)) as a composite nanofiber. Computational calculation using density functional theory (DFT) reveals that tensile strain plays a critical role in the dynamical stabilization of γ-CsPbI3. This tensile strain is triggered by the electrospinning process, which aids in the formation and growth of γ-CsPbI3. In the CsPbI3-P(VDF-HFP) composite nanofiber, γ-CsPbI3 nucleates the polar ß-crystalline phase in P(VDF-HFP), which results in the intrinsic piezo- and ferroelectric characteristics. The γ-CsPbI3 aids in preferable molecular dipole orientation, resulting in improved nanoscale piezo- and ferroelectric properties. The composite nanofiber features a higher piezoelectric d33 magnitude (∼30 pm/V) and lower decay constant for polarized domains (τcomposite ≈ 17). The composite was utilized as a piezoelectric nanogenerator to demonstrate human physiological motion monitoring in self-power mode. The relevant pressure sensitivities of 81 and 40 mV/kPa for the low-pressure (<0.6 kPa) and high-pressure (>0.6 to 12 kPa) ranges, respectively, promise its suitability in the health care sector.

Theoretical study of Cr2X3S3(X = Br, I) monolayers for thermoelectric and spin caloritronics properties.

High curie temperature 2D materials are important for the progress of the field of spin caloritronics. The spin Seebeck effect and conventional thermoelectric figure of merit (ZT) can give a great insight into how these 2D magnetic materials will perform in spin caloritronics applications. Here in this paper, we have systematically studied 2D Janus monolayers based on CrX3monolayers. We obtain a ZT of 0.31 and 0.21 for the Cr2Br3S3and Cr2I3S3Janus monolayers. The spin Seebeck coefficient obtained at room temperature is also very high (∼1570µVK-1in the hole-doped region and ∼1590µVK-1in the electron-doped region). The thermal conductivity of these monolayers (∼22 Wm-1K-1for Cr2Br3S3and ∼16 Wm-1K-1for Cr2I3S3) are also very similar to other 2D semiconductor transition metals chalcogenides. These findings suggest a high potential for these monolayers in the spin caloritronics field.

Theoretical model for predicting thermoelectric properties of tin chalcogenides.

The global energy crisis demands the search for new materials for efficient thermoelectric energy conversion. Theoretical predictive modelling with experiments can expedite the global search of novel and ecoconscious thermoelectric materials. The efficiency of thermoelectric materials depends upon the thermoelectric figure of merit (ZT). In this perspective, we discuss the theoretical model to calculate thermoelectric properties. Different scattering mechanisms of electrons and phonons are calculated using a simple model for the fast prediction of thermoelectric properties. Thermoelectric properties based on the simple model have shown more than 90% agreement with the experimental values. Possibility to optimize the figure of merit by alloying, defects, nanostructuring and band convergence is also discussed for layered chalcogenides of tin. In the case of doped materials, ion-impurity scattering is found to be dominating over electron-phonon scattering and the power factor can be optimized by tuning the former scattering rate. For phonon transport, alloy scattering is found to be the most dominating among all other scattering mechanisms. Theoretically, it is found that in the temperature range between 300 K and 800 K, SnSe0.70S0.30 has the highest ZT with an efficiency of 17.20% with respect to Carnot efficiency. There could be 53.8% enhancement of the device efficiency in SnSe0.70S0.30 compared to experimentally reported SnSe0.50S0.50 in the medium temperature range (300 K to 800 K). Possible routes to achieve the best ZT in the medium temperature range are also discussed in this perspective.

Effect of alloying on thermal conductivity and thermoelectric properties of CoAsS and CoSbS.

The effect of alloying on the thermoelectric properties of cobaltite, CoAsS, and paracostibite, CoSbS, has been investigated in this study. Density functional theory and the Boltzmann transport equation have been applied to explore the role of phonon-phonon scattering and atomistic scattering due to alloying in phonon transport. An almost 44% reduction in thermal conductivity of CoAs0.8Sb0.2S alloy compared to pure CoAsS and an ∼15% reduction in thermal conductivity of CoAs0.2Sb0.8S compared to pure CoSbS were found. Simultaneously, the thermoelectric (TE) figure of merit (ZT) increased by ∼11% in p-type CoAs0.8Sb0.2S alloy and ∼8% in n-type CoAs0.2Sb0.8S alloy as compared to their base pure materials at 800 K. We found that by tuning the composition of CoAsxSb(1-x)S alloy, very similar ZT values for both p-type and n-type can be achieved in a large temperature range. We also calculated the TE properties of CoAsSe(1-x)Sx and CoSbS(1-x)Sex alloys. This study will help in designing CoAsxSb(1-x)S based alloys for efficient thermoelectric devices.

The mechanism of nanoparticle-mediated enhanced energy transfer during high-intensity focused ultrasound sonication.

In this combined experimental and theoretical research, magnetic nano-particle (mNP) mediated energy transfer due to high intensity-focused ultrasound (HIFU) sonication has been evaluated. HIFU sonications have been performed on phantoms containing three different volume percentages (0%, 0.0047%, and 0.047%) of mNPs embedded in a tissue mimicking material (TMM). A theoretical model has been developed to calculate the temperature rise in the phantoms during HIFU sonication. It is observed from theoretical calculation that the phonon layer at the interface of the mNPs and TMM dominates the attenuation for higher (0.047%) concentration. However, for a lower concentration (0.0047%) of mNPs, intrinsic absorption is the dominating mechanism. Attenuation due to the viscous drag becomes the dominating mechanism for larger size mNPs (>1000 nm). At a higher concentration (0.047%), it is observed from theoretical calculations that the temperature rise is 25% less for gold nano-particles (gNPs) when compared to mNPs. However, at lower concentrations (0.0047% and 0.002%), the difference in temperature rise for the mNPs and gNPs is less than 2%.

Integrated computational materials discovery of silver doped tin sulfide as a thermoelectric material.

Accelerating the discovery of new materials is crucial for realizing the vision of need-driven materials development. In the present study we employ an integrated computational and experimental approach to search for new thermoelectric materials. High-throughput first principles calculations of thermoelectric transport coefficients are used to screen sulfide compounds conforming to the boundary conditions of abundant and innocuous components. A further computational screening step of substitutional defects is introduced, whereby SnS doped with monovalent cations is identified as having favorable transport properties. By silver doping of SnS under S-rich conditions an electric conductivity more than an order of magnitude higher than reported previously is realized. The obtained thermoelectric power-factor at room temperature is comparable to the state of the art for thermoelectric materials based on earth abundant, non-toxic elements. The high-throughput screening of extrinsic defects solves a long standing bottleneck in search of new thermoelectric materials. We show how the intrinsic carrier concentration in the low-temperature phase of SnSe is two orders of magnitude higher than in SnS. We furthermore find that the carrier concentration in SnSe can still be further optimized by silver doping.

Enhanced thermoelectric performance of a wide-bandgap twisted heterostructure of graphene and boron nitride.

The manipulation of the relative twist angle between consecutive layers in two-dimensional (2D) materials dramatically modulates their electronic characteristics. Twisted bilayer graphene (tblg) and twisted boron nitride (tBN) exhibit Moiré patterns that have the potential to revolutionize various fields, from electronics to quantum materials. Here, the electronic and thermoelectric properties of 21.8° tblg and 21.8° tBN and a 21.8° twisted graphene/boron nitride (Gr/BN) heterostructure were investigated using density functional theory and Boltzmann transport theory. The twisted Gr/BN heterostructure possesses a wide band gap of 1.95 eV, which overcomes the limitations of the absence of a band gap of graphene and boron nitride's extremely wide band gap. A significant increase in thermoelectric power factor was obtained for the heterostructure compared to its parent materials, 21.8° tblg and 21.8° tBN. It has a thermal conductivity of 5.88 W m-1 K-1 at 300 K, which is much lower than those of 21.8° tblg and 21.8° tBN. It is observed that graphene plays an important role in electron transport or power factor enhancement, whereas BN helps in reducing the thermal conductivity in twisted Gr/BN systems. A strong role of boundary scattering in thermal transport compared to electrical transport was observed. A high figure of merit (ZT) of 1.28 for the twisted Gr/BN heterostructure at a ribbon width of L = 10 nm and T = 900 K was obtained. This suggests its suitability as an effective material for thermoelectric applications.

Engineering piezoelectricity at vdW interfaces of quasi-1D chains in 2D Tellurene.

Low-dimensional piezoelectrics have drawn attention to the realization in nano-scale devices with high integration density. A unique branch of 2D Tellurene bilayers formed of weakly interacting quasi-1D chains via van der Waals forces is found to exhibit piezoelectricity due to the semiconducting band gap and spatial inversion asymmetry. Various bilayer stackings are systematically examined using density functional theory, revealing optimal piezoelectricity when dipole arrangements are identical in each layer. Negative piezoelectricity has been observed in two of the stackings AA' and AA″ while other two stackings exhibit the usual positive piezoelectric effect. The layer-dependent 2D piezoelectricity (∣e222D ∣) increases with an increasing number of layers in contrast to the odd-even effect observed in h-BN and MoS2. Notably, the piezoelectric effect is observed in even-layered structures due to the homogeneous stacking in multilayers. Strain is found to enhance in-plane piezoelectricity by 4.5 times (-66.25 × 10-10C m-1at -5.1% strain) due to the increasing difference in Born effective charges of positively and negatively charged Te-atoms under compressive biaxial strains. Moreover, out-of-plane piezoelectricity is induced by applying an external electric field, thus implying Tellurene is a promising candidate for piezoelectric sensors.

Unleashing the synergistic potential of 2D-2D nanosheet based S-scheme heterojunction: Cooperative boosting of CO2 reduction to solar fuel and biomass valorization.

Harnessing inexhaustible solar energy for CO2 valorization is  substantial step toward achieving  carbon-neutral energy cycle. However, CO2 conversion often exhibits slow kinetics, necessitating the utilization of sacrificial agents making the process economically unfeasible. In the ongoing quest for sustainable and economically feasible CO2 valorization, herein the photoreduction of CO2 to CO coupled with biomass-based alcohol oxidation to fine chemicals is reported via Bi2WO6/g-C3N4 (BWO/g-CN) 2D-2D nanosheet based S-scheme heterojunction. Importantly, BWO/g-CN-60 exhibits highest photocatalytic activity with CO production rate of 6.87 mmol g-1 h-1, accompanied by >98% selectivity and selective oxidation of veratryl alcohol to veratraldehyde, with notable yield of 42% in 6 h under simulated solar light. The apparent quantum yield (AQY) of 14.3% is achieved for CO production at the wavelength of 420 nm. Additionally, the formed heterostructure results in enhanced charge separation and accelerated charge transfer kinetics as validated by PL, EIS, and photocurrent studies. EPR, 13CO2 labeling, DFT studies, and various controlled experiments provided  deeper insight into the mechanism of underlying photo-redox process. Thus, the current study presents a sustainable paradigm for CO2 mitigation by converting it into solar fuel, while synergistically producing the fine chemicals through effectively harnessing the full potential of charge carriers.

Coexistence of multiple magnetic interactions in oxygen-deficient V2O5 nanoparticles.

This paper reports on the spin glass-like coexistence of competing magnetic orders in oxygen-deficient V2O5 nanoparticles with a broad size distribution. X-ray photoelectron spectroscopy yields the surface chemical stoichiometry of nearly V2O4.65 due to significant defect density. Temperature-dependent electrical conductivity and thermopower measurements demonstrate a polaronic conduction mechanism with a hopping energy of about 0.112 eV. The V2O5-δ sample exhibits strong field as well as temperature-dependent magnetic behaviour when measured with a SQUID magnetometer, showing positive magnetic susceptibility across the temperature range of 2-350 K. Field-cooled and zero-field-cooled data indicate hysteresis, suggesting glassy behaviour. The formation of small polarons due to oxygen vacancy defects, compensated by V4+ charge defects, results in Magneto-Electronic Phase Separation (MEPS) and various magnetic exchanges, as predicted by first-principle calculations. This is evidenced by the strong hybridisation of V orbitals in the vicinity of vacant oxygen site. An increase in V4+ defects shows an antiferromagnetic (AFM) component. The magnetic diversity in undoped V2O4.9 originates from defect density and their random distribution, leading to MEPS. This involves localised spins in polarons and ferromagnetic (FM) clusters on a paramagnetic (PM) background, while V4+ dimers induce AFM interactions. Electron paramagnetic resonance spectra measured at different temperatures indicate a dominant paramagnetic signal at a g-value of 1.97 due to oxygen defects, with a broad FM resonance-like hump. Both signals diminish with increasing temperature. Neutron diffraction data rules out long-range magnetic ordering, reflecting the composition as V2O4.886. Despite the FM hysteresis, no long-range order is observed in neutron diffraction data, consistent with the polaron cluster-like FM with MEPS nature. This detailed study shall advance the understanding of the diverse magnetic behaviour observed in undoped non-magnetic systems.

Electronic redistribution through the interface of MnCo2O4-Ni3N nano-urchins prompts rapid In situ phase transformation for enhanced oxygen evolution reaction.

One of the most coveted objectives in the realm of energy conversion technologies is the development of highly efficient and economically viable electrocatalysts for the oxygen evolution reaction. The commercialization of such techniques has thus far been impeded by their slow response kinetics. One of the many ways to develop highly effective electrocatalysts is to judiciously choose a coupling interface that maximizes catalyst performance. In this study, the in situ electrochemical phase transformation of MnCo2O4-Ni3N into MnCo2O4-NiOOH is described. The catalyst has an exceptional overpotential of 224 mV to drive a current density of 10 mA cm-2. Strong interfacial contact is seen in the MnCo2O4-Ni3N catalyst, leading to a considerable electronic redistribution between the MnCo2O4 and Ni3N phases. This causes an increase in the valence state of Ni, which makes it an active site for the adsorption of *OH, O*, and *OOH (intermediates). This charge transfer facilitates the rapid phase transformation to form NiOOH from Ni3N. At a higher current density of 300 mA cm-2, the catalyst remained stable for a period of 140 h. DFT studies also revealed that the in situ-formed NiOOH on the MnCo2O4 surface results in superior OER kinetics compared to that of NiOOH alone.

Harnessing Environmental Sensitivity in SnSe-Based Metal-Semiconductor-Metal Devices: Unveiling Negative Photoconductivity for Enhanced Photodetector Performance and Humidity Sensing.

The extreme sensitivity of 2D-layered materials to environmental adsorbates, which is typically seen as a challenge, is harnessed in this study to fine-tune the material properties. This work investigates the impact of environmental adsorbates on electrical properties by studying metal-semiconductor-metal (MSM) devices fabricated on CVD-synthesized SnSe flakes. The freshly prepared devices exhibit positive photoconductivity (PPC), whereas they gradually develop negative photoconductivity (NPC) after being exposed to an ambient environment for ∼1 day. While the photodetectors based on positive photoconductivity exhibit a responsivity and detectivity of 6.1 A/W and 5.06 × 108 Jones, the same for the negative photoconductivity-based photodetector reaches up to 36.3 A/W and 1.49 × 109 Jones, respectively. In addition, the noise-equivalent power of the NPC photodetector decreases by 300 times as compared to the PPC device, which implies a prominent detection capability of the NPC device against weak photo signals. To substantiate the hypothesis that negative photoconductivity stems from the photodesorption of water and oxygen molecules on the dangling bonds of SnSe flakes, the flakes are etched along the most active planes (010) with a focused laser beam in an inert environment, which enhances responsivity by 43%, supporting negative photoconductivity linked to photodesorption. Furthermore, the humidity-dependent dark current variation of the NPC photodetectors is used to design a humidity sensor for human respiration monitoring with faster response and recovery times of 0.72 and 0.68 s, respectively. These findings open up the possibility of tuning the photoelectrical response of layered materials in a facile manner to develop future sensors and optoelectronic multifunctional devices.

Quasi-harmonic approach to evaluate pyroelectric properties in Janus CrSeBr monolayer.

Two-dimensional materials are emerging as promising dielectric materials and have enormous possibilities in wearable micro and nanoelectronics, sensor, and detectors. The theoretical calculation is performed to investigate the pyroelectric coefficient and pyroelectric figure of merit (FOM) of Janus CrSeBr monolayer. Quasi-harmonic approximation (QHA) is used to calculate primary (p1) and secondary (p2) pyroelectric coefficients. Spontaneous polarization is calculated for different temperatures using QHA. Pyroelectric coefficient (1.21 µC m-2 K at 300 K) is obtained for CrSeBr monolayer, which is∼5times higher compared to MoSSe monolayer. A high FOM is found for CrSeBr monolayer(Fv=0.035 m2 C-1),(Fi=1.97 pm V-1). High FOM for voltage responsivity of CrSeBr monolayer could be beneficial for several commercial applications.

Electronic redistribution over the active sites of NiWO4-NiO induces collegial enhancement in hydrogen evolution reaction in alkaline medium.

The activity-enhancement of a new-generation catalyst focuses on the collegial approach among specific solids which exploit the mutual coactions of these materials for HER applications. Strategic manipulation of these solid interfaces typically reveals unique electronic states different from their pure phases, thus, providing a potential passage to create catalysts with excellent activity and stability. Herein, the formation of the NiWO4-NiO interface has been designed and synthesized via a three-step method. This strategy enhances the chance of the formation of abundant heterointerfaces due to the fine distribution of NiWO4 nanoparticles over Ni(OH)2 sheets. NiWO4-NiO has superior HER activity in an alkaline (1 M KOH) electrolyte with modest overpotentials of 68 mV at 10 mA cm-2 current density. The catalyst is highly stable in an alkaline medium and negligible change was observed in the current density even after 100 h of continuous operation. This study explores a unique method for high-performance hydrogen generation by constructing transition metal-oxides heterojunction. The XPS studies reveal an electronic redistribution driven by charge transfer through the NiWO4-NiO interface. The density functional theory (DFT) calculations show that the NiWO4-NiO exhibits a Pt-like activity with the hydrogen Gibbs free energy (ΔGH*) value of 0.06 eV compared to the Pt(ΔGH* = -0.02 eV).

Bio-piezoelectric phenylalanine-αß-dehydrophenylalanine nanotubes as potential modalities for combinatorial electrochemotherapy in glioma cells.

Bio-piezoelectric materials are endowed with characteristic features such as non-invasiveness, small energy attenuation and deep tissue penetrability. Thus, they have the ability to serve as both diagnostic and therapeutic modalities for targeting and treating various dreaded disorders scourging mankind. Herein, piezoelectric nanotubes derived from a modified amino acid-containing dipeptide, phenylalanine-αß-dehydrophenylalanine (Phe-ΔPhe; FΔF), possessing acoustic stimulation-triggered reactive oxygen species (ROS) generating ability, were employed and projected for achieving a piezo-active response enabled anti-cancer effect in glioma cells. A model anti-cancer drug doxorubicin (Dox) was also loaded into the nanotubes and the combined system depicted enhanced ROS production and cell killing under an acoustically developed piezo-catalytic environment. Cellular level assessment studies demonstrated that the dipeptide based piezoelectric nanotubes could lead to an increase in the cellular Ca2+ ion concentration, further inducing ROS-triggered cytotoxicity accompanied by high therapeutic efficacy in C6 glioma cells. Overall, our structures have the uniqueness of serving as acoustic stimulus-driven, wireless, and non-invasive electro-chemotherapeutic agents for enabling heightened cancer cell killing and may complement other chemotherapeutic modalities for treating the disease.

Biomass-derived cellulose nanofibers and iron oxide-based nanohybrids for thermal insulation application.

In recent years, due to high energy consumption in the building sector and subsequent environmental issues, environment-friendly and cost-effective thermally insulating materials are in high demand to improve the energy efficiency of buildings. Current commercially available thermal insulating materials (polystyrene) always pose a challenge due to their non-biodegradability and poor insulating performance. To this end, biomass-derived aerogels are attracting significant interest as renewable and sustainable insulating materials. In this work, we have developed a facile strategy for synthesizing cellulose nanofibers from biomass-derived wood pulp as a cost-effective starting material by TEMPO-oxidation, and further incorporating iron oxide nanoparticles to make a nanohybrid. Interestingly, in these nanohybrids, the functional attributes like mechanical strength and flammability were improved to a great extent and thus overcoming the limitations of the commercially available thermal insulating materials in terms of their stability and durability. Most importantly, these nanohybrids demonstrated very low thermal conductivity, as low as 0.024 W m-1 K-1, indicating the better insulating potential of these nanohybrids as compared to other conventional insulating materials.

Interfacial interaction induced OER activity of MOF derived superhydrophilic Co3O4-NiO hybrid nanostructures.

Electrocatalytic water splitting is one of the key technologies for future energy systems envisioned for the storage of energy obtained from variable renewables and green fuels. The development of efficient, durable, Earth-abundant and cheap electrocatalysts for the oxygen evolution reaction is a scorching area of research. The oxygen evolution reaction has huge potential for fuel cell and metal-air battery applications. Herein, we reported interfacially interacted and uniformly decorated Co3O4-NiO hybrid nanostructures formed by a metal-organic framework (Co2-BDC(OH)2) using BDC as a linker to the metal center. The fine nanosheets of Co2-BDC(OH)2 were first uniformly grown over the honeycomb-like structure of nickel foam (NF). After controlled calcination of these nanosheets/NF composites, a uniformly decorated, binder-free Co3O4-NiO/NF electrocatalyst was synthesized. The transformation of Co2-BDC(OH)2/NF into Co3O4-NiO/NF was characterized by several techniques such as powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy, transmission electron microscopy, etc. The catalyst exhibits a low overpotential of 311 mV vs. RHE at 10 mA cm-2 current density. The catalyst also shows long-term stability (24 h) with a Tafel slope value of 90 mV dec-1. The obtained experimental results are also in-line with the theoretical data acquired from model systems.

Super-Hydrophilic Leaflike Sn4P3 on the Porous Seamless Graphene-Carbon Nanotube Heterostructure as an Efficient Electrocatalyst for Solar-Driven Overall Water Splitting.

Water splitting using renewable energy resources is an economic and green approach that is immensely enviable for the production of high-purity hydrogen fuel to resolve the currently alarming energy and environmental crisis. One of the effective routes to produce green fuel with the help of an integrated solar system is to develop a cost-effective, robust, and bifunctional electrocatalyst by complete water splitting. Herein, we report a superhydrophilic layered leaflike Sn4P3 on a graphene-carbon nanotube matrix which shows outstanding electrochemical performance in terms of low overpotential (hydrogen evolution reaction (HER), 62 mV@10 mA/cm2, and oxygen evolution reaction (OER), 169 mV@20 mA/cm2). The outstanding stability of HER at least for 15 days at a high applied current density of 400 mA/cm2 with a minimum loss of potential (1%) in acid medium infers its potential compatibility toward the industrial sector. Theoretical calculations indicate that the decoration of Sn4P3 on carbon nanotubes modulates the electronic structure by creating a higher density of state near Fermi energy. The catalyst also reveals an admirable overall water splitting performance by generating a low cell voltage of 1.482 V@10 mA/cm2 with a stability of at least 65 h without obvious degradation of potential in 1 M KOH. It exhibited unassisted solar energy-driven water splitting when coupled with a silicon solar cell by extracting a high stable photocurrent density of 8.89 mA/cm2 at least for 90 h with 100% retention that demonstrates a high solar-to-hydrogen conversion efficiency of ∼10.82%. The catalyst unveils a footprint for pure renewable fuel production toward carbon-free future green energy innovation.