Recent Advances in Rechargeable Metal-CO2 Batteries with Nonaqueous Electrolytes.

This review article discusses the recent advances in rechargeable metal-CO2 batteries (MCBs), which include the Li, Na, K, Mg, and Al-based rechargeable CO2 batteries, mainly with nonaqueous electrolytes. MCBs capture CO2 during discharge by the CO2 reduction reaction and release it during charging by the CO2 evolution reaction. MCBs are recognized as one of the most sophisticated artificial modes for CO2 fixation by electrical energy generation. However, extensive research and substantial developments are required before MCBs appear as reliable, sustainable, and safe energy storage systems. The rechargeable MCBs suffer from the hindrances like huge charging-discharging overpotential and poor cyclability due to the incomplete decomposition and piling of the insulating and chemically stable compounds, mainly carbonates. Efficient cathode catalysts and a suitable architectural design of the cathode catalysts are essential to address this issue. Besides, electrolytes also play a vital role in safety, ionic transportation, stable solid-electrolyte interphase formation, gas dissolution, leakage, corrosion, operational voltage window, etc. The highly electrochemically active metals like Li, Na, and K anodes severely suffer from parasitic reactions and dendrite formation. Recent research works on the aforementioned secondary MCBs have been categorically reviewed here, portraying the latest findings on the key aspects governing secondary MCB performances.

Photocatalytic H2 O2 Production by Thiophene-Coupled Benzotriazole and Anthraquinone-Based D-A-Type Polymer Nanoparticles.

Herein, the photocatalytic generation of an important solar fuel-H2 O2 -by a thiophene-coupled anthraquinone (AQ) and benzotriazole-based donor (D)-acceptor (A) polymer (PAQBTz) nanoparticles is systematically reported. The visible-light active and redox-active D-A type polymer is synthesized employing the Stille coupling polycondensation, and the nanoparticles are obtained by dispersing the PAQBTz polymer and polyvinylpyrrolidone solution, prepared in tetrahydrofuran to water. The polymer nanoparticles (PNPs) produce 1.61 and 1.36 mM mg-1 hydrogen peroxide (H2 O2 ) in the acidic and neutral media, respectively, under AM1.5G simulated sunlight irradiation (λ > 420 nm) with ≈2% modified Solar to Chemical Conversion (SCC) efficiency after 1 h of visible light illumination in acidic condition. The results of the various experiments lay bare the different aspects governing H2 O2 production and indicate the H2 O2 synthesis through the superoxide anion-mediated and anthraquinone-mediated routes.

Nano-engineering of p-n CuFeO2-ZnO heterojunction photoanode with improved light absorption and charge collection for photoelectrochemical water oxidation.

The effective utilization of abundant visible solar light for photoelectrochemical water splitting is a green approach for energy harvesting, to reduce the enormous rise of carbon content in the atmosphere. Here, a novel efficient design strategy for p-n type nano-heterojunction photoanodes is demonstrated, with the goal of improving water splitting efficiency by growing low band gap p-CuFeO2 nanolayers on n-ZnO nanorods by an easy and scalable electrochemical route. The photoconversion efficiency of p-n CuFeO2/ZnO photoanodes is found to be ∼450% higher than that of pristine ZnO nanorod electrodes under visible solar light illumination (λ > 420 nm, intensity 10 mW cm-2). The p-n CuFeO2/ZnO nano-engineering not only boosts the visible light absorption but also resolves limitations regarding effective charge carrier separation and transportation due to interfacial band alignment. This photoanode also shows remarkably enhanced stability, where the formation of p-n nano-heterojunction enhances the easy migration of holes to the electrode/electrolyte interface, and of electrons to the counter electrode (Pt) for hydrogen generation. Therefore, this work demonstrates that p-n nano-engineering is a potential strategy to design light-harvesting electrodes for water splitting and clean energy generation.

Surface functionalized H2Ti3O7 nanowires engineered for visible-light photoswitching, electrochemical water splitting, and photocatalysis.

This article demonstrates comprehensive studies on different visible-light driven photoelectrochemical and photocatalytic aspects of a hydrothermally synthesized n-type H2Ti3O7 (HTO) nanowire mesh and its carbon and nitrogen functionalized counterparts, namely C-HTO and N-HTO. It was found that the presence of various defect states within the band gap of HTO, C-HTO and N-HTO nanowires, make them photoactive under visible-light. The photo-conversion efficiencies of HTO, C-HTO, and N-HTO nanowire electrodes are about 0.066, 0.129, and 0.076%, respectively, at around 1 V vs. Ag/AgCl. Carbon functionalization of HTO nanowires has been found to be most beneficial in increasing the charge carrier density, resulting in the highest current density, high photo conversion efficiency, remarkable photoelectrochemical water splitting performance and enhanced photocatalytic activity. The photocurrent density of the C-HTO NWs was found to be 0.0562 mA cm-2 at 1 V vs. Ag/AgCl, which is almost two times that of the pristine HTO NWs (0.029 mA cm-2). Although nitrogen functionalization increases the charge carrier density of the HTO nanowires, nitrogen incorporation produces lots of recombination centres in the nanowires, which are found to play a detrimental role in the photoelectrochemical and photocatalytic performance of N-HTO nanowires, limiting the expected performance. Therefore, the present study demonstrates a suitable surface engineering technique for nanostructures to maximize the utilization of green solar light.

Modeling maize growth and nitrogen dynamics using CERES-Maize (DSSAT) under diverse nitrogen management options in a conservation agriculture-based maize-wheat system.

Agricultural field experiments are costly and time-consuming, and often struggling to capture spatial and temporal variability. Mechanistic crop growth models offer a solution to understand intricate crop-soil-weather system, aiding farm-level management decisions throughout the growing season. The objective of this study was to calibrate and the Crop Environment Resource Synthesis CERES-Maize (DSSAT v 4.8) model to simulate crop growth, yield, and nitrogen dynamics in a long-term conservation agriculture (CA) based maize system. The model was also used to investigate the relationship between, temperature, nitrate and ammoniacal concentration in soil, and nitrogen uptake by the crop. Additionally, the study explored the impact of contrasting tillage practices and fertilizer nitrogen management options on maize yields. Using field data from 2019 and 2020, the DSSAT-CERES-Maize model was calibrated for plant growth stages, leaf area index-LAI, biomass, and yield. Data from 2021 were used to evaluate the model's performance. The treatments consisted of four nitrogen management options, viz., N0 (without nitrogen), N150 (150 kg N/ha through urea), GS (Green seeker-based urea application) and USG (urea super granules @150kg N/ha) in two contrasting tillage systems, i.e., CA-based zero tillage-ZT and conventional tillage-CT. The model accurately simulated maize cultivar's anthesis and physiological maturity, with observed value falling within 5% of the model's predictions range. LAI predictions by the model aligned well with measured values (RMSE 0.57 and nRMSE 10.33%), with a 14.6% prediction error at 60 days. The simulated grain yields generally matched with measured values (with prediction error ranging from 0 to 3%), except for plots without nitrogen application, where the model overestimated yields by 9-16%. The study also demonstrated the model's ability to accurately capture soil nitrate-N levels (RMSE 12.63 kg/ha and nRMSE 12.84%). The study concludes that the DSSAT-CERES-Maize model accurately assessed the impacts of tillage and nitrogen management practices on maize crop's growth, yield, and soil nitrogen dynamics. By providing reliable simulations during the growing season, this modelling approach can facilitate better planning and more efficient resource management. Future research should focus on expanding the model's capabilities and improving its predictions further.

Battery Performance Amelioration by Introducing a Conducive Mixed Electrolyte in Rechargeable Mg-O2 Batteries.

With magnesium being a cost-effective anode metal compared to the other conventional Li-based anodes in the energy market, it could be a capable source of energy storage. However, Mg-O2 batteries have struggled its way to overcome the poor cycling stability and sluggish reaction kinetics. Therefore, Ru metallic nanoparticles on carbon nanotubes (CNTs) were introduced as a cathode for Mg-O2 batteries, which are known for their inherent electronic properties, large surface area, and increased crystallinity to favor remarkable oxygen reduction reactions and oxygen evolution reactions (ORR and OER). Also, we deployed a first-of-its-kind, conducive mixed electrolyte (CME) (2 M Mg(NO3)2:1 M Mg(TFSI)2/diglyme). Hence, this synergistic incorporation of CME-based Ru/CNT Mg-O2 batteries could unleash long cycle life with low overpotential, excellent reversibility, and high ionic conductivity and also reduces the intrinsic corrosion behavior of Mg anodes. Correspondingly, this novel amalgamation of CME with Ru/CNT cathode has displayed superior cyclic stability of 65 cycles and a maximum discharge potential of 25 793 mAh g-1 with a small overvoltage plateau of 1.4 V, noticeably subjugating the findings of conventional single electrolyte (CSE) (1 M Mg(TFSI)2/diglyme). This CME-based Ru/CNT Mg-O2 battery design could have a significant outcome as a future battery technology.

Effect of defect-rich Co-CeOx OER cocatalyst on the photocarrier dynamics and electronic structure of Sb-doped TiO2 nanorods photoanode.

This work demonstrates the in-depth mechanism of enhanced photoelectrochemical (PEC) water oxidation of Sb-doped rutile TiO2 nanorods (NRs) photoanode coupled with oxygen vacancy defect-rich Co-doped CeOx (Co-CeOx) oxygen evolution reaction (OER) cocatalyst. The defect-rich Co-CeOx cocatalyst modification improves the conductivity, light absorption, charge transfer efficiency, and surface photovoltage generation of the Co-CeOx/Sb-TiO2 hybrid NRs photoanode. The Co-CeOx cocatalyst also serves as the surface passivating overlayer for the Sb-TiO2 photoanode, which suppresses the surface states mediated recombination of electron-hole pairs in the NRs. The PEC studies further indicate that Co-CeOx cocatalyst induces remarkably large band bending at the semiconductor/electrolyte interface and shortens the carrier diffusion length and depletion layer width, facilitating the rapid separation and transportation of the photocarriers for the surface PEC reactions. The experimental and theoretical studies confirm that the Co-doping in CeOx cocatalyst enhances the surface oxygen vacancy defects, which provides active catalytic sites for OH- adsorption and charge transportation for enhanced OER kinetics. The density functional theory (DFT) calculations demonstrate a higher conductivity of the Co-CeOx cocatalyst, advantageous for rapid charge transfer capability during PEC reactions. The synergy between all these merits helps the optimized Co-CeOx/Sb-TiO2 photoanode to deliver a maximum photocurrent density of 1.41 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (VRHE) and an ultra-low turn on potential (Von) of 0.1 VRHE under AM 1.5G solar illumination compared to the Sb-TiO2 NRs (0.96 mA cm-2 at 1.23 VRHE and Von = 0.42 VRHE). This work demonstrates the design of an efficient defect-rich cocatalyst modified photoanode for solar energy harvesting.

Pt nanoparticles coupled with perylene-based small molecule deposited on Ti3+ self-doped TiO2 nanorods-An inorganic/organic type-II nanoheterostructure for efficient visible-light photoelectrochemical water oxidation.

In the work reported in this article, we have coupled Ti3+-self-doped TiO2 nanorods (NRs) with a newly synthesized tetrathiophene coupled perylene-based molecule (tThTMP) to form type-II inorganic/organic nanoheterostructures (NHs) for visible-light-driven water oxidation. The small organic molecule helps in better utilizing a wide range of the visible light spectrum, facilitates a faster delocalization of the photogenerated carriers at the inorganic/organic heterojunction, and exhibits improved photoelectrochemical performances. We have further decorated the NHs with platinum nanoparticles (NPs). The decoration of the Pt NPs significantly augments the various aspects of photoelectrochemical performances. The Pt NPs decorated NHs photoanode exhibits a photocurrent density of 0.83 mA/cm2 at 1.23 V vs. RHE (@10 mV/s scan rate), a photoconversion efficiency of 0.26%, a substantial cathodic shift in the water oxidation onset potential and flat band potential, impressively reduced charge transfer resistance, improved photocarrier concentration, photovoltage, and stability.

Cultivation of microalgae on food waste: Recent advances and way forward.

Microalgae are photosynthetic microbes that can synthesize compounds of therapeutic potential with wide applications in the food, bioprocessing and pharmaceutical sector. Recent research advances have therefore, focused on finding suitable economic substrates for the sustainable cultivation of microalgae. Among such substrates, food derived waste specifically from the starch, meat, dairy, brewery, oil and fruit and vegetable processing industries has gained popularity but poses numerous challenges. Pretreatment, dilution of waste water supernatants, mixing of different food waste streams, utilizing two-stage cultivation and other biorefinery approaches have been intensively explored for multifold improvement in microalgal biomass recovery from food waste. This review discusses the advances and challenges associated with cultivation of microalgae on food waste. The review suggests that there is a need to standardize different waste substrates in terms of general composition, genetically engineered microalgal strains, tackling process scalability issues, controlling wastewater toxicity and establishing a waste transportation chain.

4nπ Stable Multitasking Azapentacene: Acidochromism, Hole Mobility, and Visible Light Photoresponse.

Herein, we describe the synthesis, characterization, and optoelectronic investigation of a stable 4nπ dihydrotetraazapentacene derivative. The neutral dihydrotetraazapentacene contains a 24π-conjugated N-heteroacene core with two phenyl pendants appended thereof. The exceptional stability of this formally antiaromatic π-system is attributed to the fused dihydropyrazine ring, which has ethenamine (enamine) conjugations, and hence, the π-electrons delocalize over the nearly planar azapentacene core to endow with a global aromatic characteristic. The embedded dihydropyrazine also offers an additional Clar's sextet with enhanced aromaticity. The present dihydrotetraazapentacene can be considered as a multitasking N-heteroacene, which showed photoresponsive nature under visible light illumination, acidochromism in solution, and p-type charge transport with an appreciable field-effect hole mobility of 0.02 cm2 V-1 s-1 and a bulk p-type mobility of 0.98 × 10-4 cm2 V-1 s-1 in the space charge-limited regime of operation measured in the hole-only device. Nucleus-independent chemical shift calculation, anisotropy of the induced current density plot, and anisotropic mobility calculation were performed to support the experimental findings.

Localized surface plasmon-enhanced photoelectrochemical water oxidation by inorganic/organic nano-heterostructure comprising NDI-based D-A-D type small molecule.

This research article reports the visible-light-driven photoelectrochemical water oxidation performances of the plasmonic Au-Pd nanoparticle-decorated inorganic/organic nano-heterostructures (NHs)-B-TiO2/NDIEHTh@Au-Pd. The inorganic constituent of the NHs consists of boron-doped TiO2 nanorods (NRs) grown on fluorine-doped tin oxide (FTO) coated glass substrate. The organic part (NDIEHTh) consists of an acceptor naphthalene diimide (NDI)-based donor-acceptor-donor (D-A-D) type small molecule, in which thiophene serves as the donor. Because of the benefits of the localized surface plasmon resonance (LSPR) effect, the Au-Pd binary alloy nanoparticles substantially ameliorate the visible-light-driven photoelectrochemical performances of the B-TiO2/NDIEHTh@Au-Pd NHs photoanode compared to the B-TiO2/NDIEHTh NHs photoanode. The photocurrent densities exhibited by the B-TiO2/NDIEHTh NHs, and B-TiO2/NDIEHTh@Au-Pd NHs photoanodes at 1 V vs Ag/AgCl are 0.68 mA/cm2 and 1.59 mA/cm2, respectively, manifesting 209% and 623% increments in the photocurrent density compared to that shown by B-TiO2 NRs photoanode. Besides, the B-TiO2/NDIEHTh@Au-Pd NHs photoanode offers a significantly cathodically shifted water oxidation potential, reduced charge transfer resistance, better surface injection efficiency, and most importantly, superior photostability compared to the B-TiO2/NDIEHTh NHs photoanode. The enhancement in the different photoelectrochemical performances could be attributed to the various advantages of LSPR, such as enhanced light absorbance, light concentration, hot electron injection, and plasmon-induced resonance energy transfer.

The formation and detection techniques of oxygen vacancies in titanium oxide-based nanostructures.

TiO2 and other titanium oxide-based nanomaterials have drawn immense attention from researchers in different scientific domains due to their fascinating multifunctional properties, relative abundance, environmental friendliness, and bio-compatibility. However, the physical and chemical properties of titanium oxide-based nanomaterials are found to be explicitly dependent on the presence of various crystal defects. Oxygen vacancies are the most common among them and have always been the subject of both theoretical and experimental research as they play a crucial role in tuning the inherent properties of titanium oxides. This review highlights different strategies for effectively introducing oxygen vacancies in titanium oxide-based nanomaterials, as well as a discussion on the positions of oxygen vacancies inside the TiO2 band gap based on theoretical calculations. Additionally, a detailed review of different experimental techniques that are extensively used for identifying oxygen vacancies in TiO2 nanostructures is also presented.