Simulated Solar Illumination Research Articles

A hybrid solar and RF energy harvester for applications of self-Powered wireless sensor nodes

A hybrid solar and RF energy harvester is proposed for applications in self-powered wireless sensor nodes. A planar slot antenna array backed by substrate integrated waveguide (SIW) cavity is produced for RF energy harvesting. A designed rectifier connected to the antenna array converts the received RF energy into DC energy. Solar cells are placed on the rest of the antenna array except slots, fully utilizing the array's surface. The solar cell coverage ratio reaches 87%. The measurement results indicate that under solar simulator illumination, the solar energy harvester has a short-circuit current of 15.7 A, an open-circuit voltage of 0.542 V, and a maximum output power of 5.81 W. Under the RF power density of 85.5 μW/cm2, the RF energy harvester reaches its peak power conversion efficiency (PCE) of 69%. All simulated and measured results are in good agreement, verifying the capabilities of the designed hybrid harvester.

Dimerized Non-Fullerene Acceptor-based organic photovoltaics for Round-the-Clock functioning

Organic photovoltaics (OPVs) have emerged as a key sustainable energy technology capable of efficiently generating electricity from both direct sunlight and low-intensity indoor lighting. Despite ongoing research to improve their performance, limited efforts have been undertaken to develop OPVs that can operate consistently (24/7/365) under versatile lighting conditions. For effective utilization, OPVs must demonstrate efficient operation under both outdoor and indoor illumination conditions, generating sufficient electrical power to drive microelectronic devices. Low-bandgap non-fullerene acceptors (NFAs) in OPVs are limited by low open-circuit voltage (VOC) under indoor lighting, restricting their performance. While high-bandgap NFAs can improve indoor power-conversion efficiency (PCE) by elevating VOC, they may often reduce outdoor performance owing to reduced light harvesting. Thus, we developed OPVs using the oligomeric dimerized NFA DYBO, which simultaneously achieved an excellent PCE of 16.7 % under simulated solar illumination and a remarkable maximum power output density (Pmax) of 0.079 and 0.396 mW/cm2 under a 5,200 K LED and halogen lamp (1000 lx), respectively, attributed to elevated VOC and reduced short-circuit current density (JSC) losses. The optimized OPVs demonstrated PCEs nearly equivalent to those of the current state-of-the-art under indoor illumination, with a remarkable Pmax capable of autonomously powering a variety of microelectronic devices.

Enhanced solar-powered H2 production from water splitting and sustainable wastewater treatment using interface-engineered ZnIn2S4/TiO2/Ti3C2 S-scheme heterocatalyst

Developing efficient photocatalysts that can degrade persistent antibiotics in water bodies and generate clean H2 through water splitting is crucial for environmental and energy sustainability. This study introduces an advanced hierarchical ZnIn2S4/TiO2/Ti3C2 (ZIS/TO/TC) heterocatalyst for the efficient removal of amoxicillin (AXC) from wastewater and the production of H2 through water reduction process under simulated solar illumination. The ZIS/TO/TC hybrids were fabricated via an in situ hydrothermal process, resulting in a hierarchical 3D structure that capitalizes on the complementary properties of each component. The design of the S-scheme heterojunction significantly enhances charge separation and transfer efficiency, offering improvements over traditional type-II or Z-scheme mechanisms. Notably, the optimized ZIS10/TO/TC hybrid catalyst demonstrated remarkable activity, achieving 100 % AXC degradation and excellent mineralization within 90 min, along with an H2 production rate of 4104 μmol h−1 g−1, significantly outperforming the individual components and exceeding previously reported efficiencies. The outstanding performance of the ZIS10/TO/TC hybrid is attributed to its enhanced light absorption properties, synergistic interactions among the ZIS, TO, and TC MXene, and the efficient S-scheme charge transfer mechanism, which facilitates effective charge separation and transfer while preserving the strong reducing and oxidizing capabilities of the components. Additionally, the ZIS10/TO/TC hybrid exhibited excellent stability over multiple photocatalytic tests, emphasizing its potential for practical applications. Therefore, this research demonstrates an advanced and highly efficient hybrid photocatalyst that offers a promising and sustainable solution for both integrated water treatment and renewable energy generation.

Photocatalytic Acetylene Hydrochlorination by Pairing Proton Reduction and Chlorine Oxidation over g-C3N4/BiOCl Catalysts.

Acetylene hydrochlorination is a vital industrial process for the manufacture of vinyl chloride monomer (VCM). Current thermocatalytic acetylene hydrochlorination requires toxic mercury-based or costly noble metal-based catalysts, high temperatures (≥180 °C) and excessive gaseous HCl. Here, we report a room-temperature photocatalytic acetylene hydrochlorination strategy involving concurrent coupling of electron-driven proton reduction (*H) and hole-driven chloride oxidation (*Cl) on photocatalyst surfaces. Under simulated solar light illumination, the developed noble-metal-free g-C3N4/BiOCl photocatalysts show a considerably high VCM production rate of 1198.6 μmol g-1 h-1 and a high VCM selectivity of 95% in a 0.1 M HCl aqueous solution. Even in chloride-rich natural seawater and acidified natural seawater, the VCM production rates of g-C3N4/BiOCl photocatalysts are up to 170.3 μmol g-1 h-1 with a VCM selectivity of 80.4% and 1247.7 μmol g-1 h-1 with a VCM selectivity of 94.7%, respectively. Moreover, with sunlight irradiation and acidified natural seawater, the g-C3N4/BiOCl photocatalysts in a large-scale photosystem retain outstanding acetylene hydrochlorination performance over 10 days of operation. The radical scavenging, in situ photochemical Fourier transform infrared spectroscopy, theoretical simulations, and control experiments reveal that active *Cl and *H play key roles in photocatalytic acetylene hydrochlorination via a possible reaction pathway of C2H2 → *C2H2 → *C2H2Cl → *C2H3Cl → C2H3Cl. With respect to sustainability and low cost, this photocatalytic acetylene hydrochlorination offers excellent advantages over conventional thermocatalytic hydrochlorination technologies.

Iron and Nickel Substituted Perovskite Cobaltites for Sustainable Oxygen Evolving Anodes in Alkaline Environment.

Perovskite oxides have great flexibility in their elemental composition, which is accompanied by large adjustability in their electronic properties. Herein, we synthesized twelve perovskites oxide-based catalysts for the oxygen evolution reaction (OER) in alkaline media. The catalysts are based on the parent oxide perovskite Ba0.5Gd0.8La0.7Co2O6-δ (BGLC587) and are synthesized through the sol-gel citrate synthesis route. To reduce the demand on cobalt (Co), but also increase the intrinsic catalytic activity of BGLC587 for the OER, we substitute Co on the B-site with certain amounts of Fe and Ni, synthesizing catalysts of the general formula Ba0.5Gd0.8La0.7Co2-x-yFexNiyO6-δ. A plethora of physicochemical and electrochemical methods suggest that an Fe content between 30% and 70% increases the intrinsic catalytic activity of BGLC587, while Tafel slopes in combination with in-situ Raman spectroscopy suggest the rate determining step is likely a proton-exchange reaction, progressing possibly through the lattice oxygen mechanism (LOM). We apply one of the optimized, Co-substituted perovskites in a monolithic, photovoltaic (PV)-driven electrolysis cell and we achieve an initial solar-to-hydrogen (STH) conversion efficiency of 10.5% under one sun solar simulated illumination.

A novel vanadium-copper rechargeable battery for solar energy conversion and storage

To enhance the utilization of abundant yet intermittent sunlight, the integration of solar energy conversion and storage has received increasing attention, and utilizing photoelectrodes to drive non-spontaneous reversible redox reactions provides a promising solution. This study proposes a triple-compartment system combining dual-photoelectrode (TiO2 and pTTh) with vanadium-copper electrolytes for integrated solar energy conversion and storage. The system can convert solar energy into chemical energy under simulated solar illumination (100 mW∙cm−2, AM 1.5G) and controllably release the stored chemical energy in the form of electrical energy. The system achieves a discharge open-circuit voltage of 0.47 V and a short-circuit current density of 1.3 mA∙cm−2. In constant current discharge tests, a discharge capacity of 2 mAh is observed at 0.3 mA∙cm−2.

Synergistic effect of oxygen vacancies and functionalized ligands selectively enhanced the photocatalytic oxidation of methane to carbon monoxide

The titanium-based metal–organic framework MIL-125(Ti) has been widely investigated in photocatalytic carbon dioxide reduction and water splitting, but rarely studied in photocatalytic methane conversion by employing only water as an oxidant under mild conditions. Simultaneously controlling products with high yield and selectivity is highly challenging in methane conversion. Herein, we develop a series of functionalized titanium metal–organic frameworks via a facile organic ligand exchange process. The abundant Ti3+ active sites induced by oxygen vacancies and functionalized ligands synergistically facilitate the adsorption and activation of methane molecules. The carbon monoxide yield over NH2-MIL-125(Ti) increased to 198.6 μmol·gcat−1·h−1 with a high selectivity of 87.1 % under simulated solar illumination. Combined with in-situ characterizations and density functional theoretical calculations, the results confirmed that Ti3+ active sites induced by oxygen vacancies and amino functional groups synergistically enhanced the photocatalytic conversion of methane and elucidate CH4-to-CO conversion mechanism. This study does not only provide insights into the rational design of metal–organic frameworks with copious oxygen vacancies and functional groups, but also provides some significant cognition for photocatalytic methane conversion.

Dual photoelectrode-drived Fe–Br rechargeable flow battery for solar energy conversion and storage: A cost-effective approach

The integrated design of solar energy conversion and storage systems has attracted increasing attention, and non-spontaneous redox reactions driven by dual photoelectrodes provide a potential solution to this issue. This study presents a solar rechargeable flow battery (SRFB) that combines dual photoelectrodes (BiVO4 or Mo–BiVO4 as photoanode, polyterthiophene (pTTh) as photocathode) with cost-effective redox pairs (Fe3+/Fe2+ and Br3−/Br−). The system charges under simulated solar illumination (100 mW∙cm−2, AM 1.5G) and releases stored energy controllably as electrical energy. Research indicates the Mo–BiVO4 photoanode and pTTh photocathode achieve an open-circuit voltage of 0.34 V and a short-circuit current density of 0.38 mA cm−2. Using a specially designed Fe3+/Fe2+-Br3−/Br− (Fe–Br) SRFB device made via 3D printing, a charging photocurrent of approximately 1.9 mA cm−2 is attained. In constant current discharge tests, an initial discharge voltage of 0.23 V is observed at 0.1 mA∙cm−2 within the 10 discharge cycles, demonstrating system stability and offering a viable solution for low-cost, large-scale solar energy storage and conversion.

Facile dual-functionalization of PEN nanofibrous membranes with solar evaporation and photocatalysis for efficient dye wastewater purification

Purification of dye wastewater by combining photocatalytic degradation with solar energy-driven interfacial water evaporation has emerged as a promising approach to address water pollution in recent years. In this work, a high-performance polymer, polyarylene ether nitrile (PEN), was electrostatically spun to construct a robust nanofibrous substrate, then dual-functionalized using polyaniline (PANI) and titanium dioxide (TiO2) via a facile polydopamine (PDA)-assisted vacuum self-assembly method. Moreover, the CA of the PEN membrane after PDA and PANI@TiO2 treatment changes from 20° to 0° within 0.4 s, showing superhydrophilic properties and providing rapid water supply for water evaporation. PANI and TiO2 were employed as the photo-thermal conversion component and photocatalytic component, respectively. The fabricated dual-functionalized PANI@TiO2/PEN composite nanofibrous membrane exhibited a high water evaporation rate of up to 3.23 kg m−2 h−1 under a simulated solar illumination of 1 KW m−2. Owing to the reduction in the photoelectron-hole recombination rate promoted by PANI, the composite nanofibrous membrane demonstrated a favorable dye removal rate of 92.18% in 6 h for methylene blue (MB). Furthermore, the robust PEN nanofibrous skeleton conferred the composite membrane with thermal resistance and corrosion resistance properties, ensuring long-term performance in harsh environments. The facile fabricated PANI@TiO2/PEN membrane achieved comprehensive performance, offering a promising strategy by combining solar-driven interfacial water evaporation and photocatalytic degradation for water purification.

Heterostructure engineering of resorcinol-formaldehyde resins and sulfur-vacancy-containing Zn3In2S6 for high-efficiency photocatalytic H2O2 production

Resorcinol-formaldehyde (RF) resins have garnered significant interest due to their remarkable efficiency in producing photocatalytic H2O2. The combination of RF with inorganic semiconductors to create organic–inorganic heterojunctions represents a promising strategy for enhancing photocatalytic activity. In this work, RF was coated onto Zn3In2S6 nanoflowers with sulfur-vacancy, creating RF/Zn3In2S6 composites with an S-scheme heterostructure. This novel composite exhibited superior photocatalytic activity for H2O2 production in both pure water and seawater, without sacrificial agents. Specifically, the production rate of RF/Zn3In2S6-0.3 in pure water under simulated solar illumination achieved 3174.34 μmol/h/g, marking 8.53 and 4.17 times over RF and Zn3In2S6, respectively. Moreover, its photocatalytic activity in seawater reached an impressive 2290.81 μmol/h/g, 4.93 and 3.12 times greater than that of RF and Zn3In2S6, respectively. The enhanced photocatalytic activity is attributed to the S-scheme charge transfer mechanism, which facilitates efficient charge separation and amplifies redox capabilities. Both experimental and density function theory analyses confirm the S-scheme route in RF/Zn3In2S6-0.3 for photocatalytic H2O2 production. This study not only presents the first account of an organic semiconductor RF being employed in an S-scheme heterojunction interface but also introduces the surface sulfur-vacancy mediated S-scheme heterojunction strategy for photocatalytic H2O2 production, representing a significant advancement in the field.

Elucidation of the optical, electronic, and photoelectrochemical properties of p-type CuFe2O4 photocathodes

High-quality thin films of p-type CuFe2O4 photocathode were prepared for the first time on FTO-coated glass substrates by a novel nonaqueous solution using spray pyrolysis method. The films' critical physical and photophysical properties, including morphology, optical properties, carrier transport properties, band position, and photoelectrochemical (PEC) characteristics, were analyzed and estimated. The feasibility of PEC water splitting was systematically evaluated. The prepared reddish-brown CuFe2O4 film exhibits a compact and uniform morphology. Its optical bandgap is approximately 1.42 eV, and it possesses a suitable conduction band position, indicating its capability to facilitate solar-driven water splitting and absorb visible light. Under AM 1.5 simulated solar illumination, the photocurrent density of 12 μA/cm2 was attained in a 1 mol NaOH solution. However, the prepared CuFe2O4 films demonstrate instability under constant light in the electrolyte owing to the copper reduction reaction. These research results offer a fresh insight into the potential application of CuFe2O4 as a photocathode semiconductor in PEC water splitting.

Synergistic effect of noble metal modified LaNiO3 perovskites for photocatalytic water splitting

Harnessing the solar energy to produce valuable fuels is a promising solution to the global energy crisis. One such vital fuel is hydrogen and it can be produced through the efficient evolution from water using a judiciously chosen perovskite photocatalyst. Perovskite materials, with their distinctive structural and optical properties, emerge as potential catalysts for visible light photocatalytic water splitting. Among these, LaNiO3 stands out as a promising photocatalyst due to its small bandgap and well-suited band edges that enable efficient visible light absorption. Strategic modifications with noble metals further elevate the photocatalytic performance. Utilizing the solution combustion method, catalysts are synthesized and extensively characterized through techniques such as XRD, XPS, ICP-OES, SEM, BET, DRS, UPS, Photoluminescence, and Time-resolved photoluminescence. Photocatalytic hydrogen evolution studies are conducted under solar simulator illumination. Notably, the addition of noble metals increased the photocatalytic activity from 1.37 mmol g-1 h-1 to 20.86 mmol g-1 h-1 while the apparent quantum efficiency varied from 2.58% to 39.42%. The TOF on the basis of the active sites varied from 214.44 h-1 to 1685.24 h-1. The catalysts demonstrate stable and consistent performance over a 12-hour duration. The photocatalytic H2 yield trend was found to be Rh/LaNiO3 > Ru/LaNiO3 > Ir/LaNiO3 > Pt/LaNiO3 > LaNiO3.

Nitrogen-doped carbon quantum dot as electron acceptor anchored on graphitic carbon nitride nanosheet for improving rhodamine B degradation

Carbon quantum dots (CQDs) hold significant promise for wastewater treatment because of their remarkable attributes, including robust stability, outstanding biocompatibility, minimal toxicity, superior water dispersibility, cost-effective production, and exceptional photo-stability.In this study, CQDs were synthesized using microplasma and tested for the degradation of rhodamine B (RhB) (5 mg/L) under different conditions, with a Solar simulator and UVA illumination. Specifically, graphitic carbon nitride nanosheets (NCN) in conjugation with carbon quantum dots (NCN@CQD) were prepared with different amounts of CQD. The synthesized CQD, NCN, and NCN@CQD underwent characterization using various compositional and structural analytical techniques. The results show that nitrogen species were effectively incorporated into the CQDs framework and CQDs are anchored on NCN forming NCN@CQD successfully. Subsequently, all samples were then investigated in degrading Rhodamin B, RhB, to assess the photocatalytic activity. The results reveal that the presence of CQDs substantially improved the photocatalytic efficiency of NCN. Specifically, the CQDs anchored on NCN exhibited a substantial enhancement in the photoactivity for RhB decomposition under a solar light simulator, surpassing that of pure NCN. The amount of CQD in the NCN@CQD sample exerted a strong influence on the photocatalytic activity. All NCN@CQD samples exhibited remarkable enhancements in both adsorption and photocatalytic performance compared to pure CQD and NCN samples. In an optimization study, a best NCN@CQ photocatalyst was identified, showing a 40 % enhancement of photocatalytic efficiency compared to the use of NCN alone. A visible light photocatalytic activity of 91 % can be attained within 150 min, exhibiting a reaction rate constant of 0.0135 min−1 toward RhB decomposition, which was double as for the individual NCN (0.0067 min−1). The boosted photocatalytic activity resulting from the synergistic effect between NCNs and CQDs can be attributed to the efficient function of CQD as an electron acceptor. The proposed mechanism of photocatalytic degradation of RhB is illustrated in detail.

Solar enhanced oxygen evolution reaction with transition metal telluride.

The photo-enhanced electrocatalytic method of oxygen evolution reaction (OER) shows promise for enhancing the effectiveness of clear energy generation through water splitting by using renewable and sustainable source of energy. However, despite benefits of photoelectrocatalytic (PEC) water splitting, its uses are constrained by its low efficiency as a result of charge carrier recombination, a large overpotential, and sluggish reaction kinetics. Here, we illustrate that Nickel telluride (NiTe) synthesized by hydrothermal methods can function as an extremely effective photo-coupled electrochemical oxygen evolution reaction (POER) catalyst. In this study, NiTe was synthesized by hydrothermal method at 145°C within just an hour of reaction time. In dark conditions, the NiTe deposited on carbon cloth substrate shows a small oxygen evolution reaction overpotential (261mV) at a current density of 10mA cm-2, a reduced Tafel slope (65.4mV dec-1), and negligible activity decay after 12h of chronoamperometry. By virtue of its enhanced photo response, excellent light harvesting ability, and increased interfacial kinetics of charge separation, the NiTe electrode under simulated solar illumination displays exceptional photoelectrochemical performance exhibiting overpotential of 165mV at current density of 10mA cm-2, which is about 96mV less than on dark conditions. In addition, Density Functional Theory investigations have been carried out on the NiTe surface, the results of which demonstrated a greater adsorption energy for intermediate -OH on the catalyst site. Since the -OH adsorption on the catalyst site correlates to catalyst activation, it indicates the facile electrocatalytic activity of NiTe owing to favorable catalyst activation. DFT calculations also revealed the facile charge density redistribution following intermediate -OH adsorption on the NiTe surface. This work demonstrates that arrays of NiTe elongated nanostructure are a promising option for both electrochemical and photoelectrocatalytic water oxidation and offers broad suggestions for developing effective PEC devices.

Unlocking photocatalytic NO removal potential in an S‐type UiO‐66‐NH2/ZnS(en)0.5 heterostructure

AbstractThe contamination of nitric oxide presents a significant environmental challenge, necessitating the development of efficient photocatalysts for remediation. Conventional heterojunctions encounter obstacles such as large contact barriers, sluggish charge transport, and compromised redox capacity. Here, we introduce an innovative S‐type heterostructure photocatalyst, UiO‐66‐NH2/ZnS(en)0.5, designed specifically to overcome these challenges. The synthesis, employing a unique microwave solvothermal method, strategically aligns the lowest unoccupied molecular orbital of UiO‐66‐NH2 with the highest occupied molecular orbital of ZnS(en)0.5, fostering the formation of a stepped heterojunction. The resulting intimate interface contact generates a built‐in electric field, facilitating charge separation and migration, as evidenced by time‐resolved photoluminescence spectroscopy and photoelectrochemical tests. The abundant active sites in the porous UiO‐66‐NH2 counterpart provide adsorption and activation sites for nitrogen monoxide (NO) oxidation. Performance evaluation reveals exceptional photocatalytic NO removal, achieving 70% efficiency and 99% selectivity toward nitrates under simulated solar illumination. Evidence from X‐ray photoelectron spectroscopy and trapping experiments supports the effectiveness of the S‐type heterostructure, showcasing refined reactive oxygen species, particularly superoxide. Thus, this study introduces a new perspective on advanced NO oxidation and unlocks the potential of S‐scheme heterojunctions to refine reactive oxygen species for NO remediation.

Efficient photocatalytic degradation of tetracycline hydrochloride by Cu2O/BiVO4 p-n heterostructure

Star-like BiVO4 and Cu2O nanocubes were prepared by hydrothermal method and chemical reduction, respectively, and Cu2O/BiVO4 p-n heterojunction with different mass ratios of Cu2O to BiVO4 (3:1, 1:1, 1:3) were synthesized via facile physical mixing. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of the Cu2O/BiVO4 composites was evaluated by degradation of tetracycline hydrochloride (TC) under simulated solar illumination. Owing to the fast charge transfer between n-type BiVO4 and p-type Cu2O, Cu2O/BiVO4 composites exhibited superior photocatalytic activity. When the mass ratio of Cu2O to BiVO4 was 1:3, the highest degradation efficiency of TC reached 78.9% within 24 min.

Highly ordered crystallization of α-FAPbI3 films via homogeneous seeds for efficient perovskite solar cells

Formamidine lead triiodide (FAPbI3) perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency (PCE). However, random nucleation, phase transition, and lattice defects are still the key challenges limiting the quality of FAPbI3 films. Previous studies show that the introduction or adding of seeds in the precursor is effective to promote the nucleation and crystallization of perovskite films. Nevertheless, the seed-assisted approach focuses on heterogeneous seeds or hetero-composites, which inevitably induce a lattice-mismatch, the generation of strain or defects, and the phase segregation in the perovskite films. Herein, we first demonstrate that high-quality perovskite films are controllably prepared using α- and δ-phases mixed FAPbI3 microcrystal as the homogeneous seeds with the one-step antisolvent method. The partially dissolved seeds with suitable sizes improve the crystallinity of the perovskite film with preferable orientation, improved carrier lifetime, and increased carrier mobility. More importantly, the α-phase-containing seeds promote the formation of α-phase FAPbI3 films, leading to the reduction of residual lattice strain and the suppression of I− ion migration. Besides, the adding of dimethyl 2,6-pyridine dicarboxylate (DPD) into the precursor further suppresses the generation of defects, contributing to the PCE of devices prepared in air ambient being significantly improved to 23.75%, among the highest PCEs for fully air-processed FAPbI3 solar cells. The unpackaged target devices possess a high stability, maintaining 80% of the initial PCE under simulated solar illumination exceeding 800 h.

Photoelectrochemical properties of anatase TiO2 nanostructures prepared by hydrothermal method: Effect of illumination and external bias on charge transport

A systematic study of photoelectrochemical properties in terms of carrier transport was conducted for TiO2 nanostructure films fabricated on Ti foil at different temperatures (130 °C–210 °C) through alkaline hydrothermal technique, along with the morphological, structural, and optical properties. For samples, the morphology transformed from nanosheets to nanowires, the phase converted from bi-phase of brookite and anatase to pure anatase along with the reduction in the amount of oxygen vacancies as temperature increases. Among them, the dark blue bi-phased TiO2 (brookite and anatase) prepared at 130 °C of hydrothermal treatment (TiO2-130) with nanosheets morphology displayed the optimum photoelectrochemical performance with the highest photocurrent density of 265 μA/cm2 at 1 V (vs. Ag/AgCl), largest carrier density of 1.809 × 1019cm−3 and narrowest space charge region of 11.73 nm. Besides, the large reduction in charge transfer resistance and the width of space charge region caused by simulated solar illumination facilitate the charge transport in photoelectrode especially the TiO2-130 with the largest reduction, indicating the great influence of illumination on carrier dynamics. Moreover, the external bias caused the reduction of resistance under irradiation, the increase in the resistance in the dark. Importantly, the TiO2-210 showed p-type conductivity under illumination inferred from the negative slope of Mott-Schottky plots, which is first observed and further confirm the influence of light on the charge transfer process.

Concurrent photocatalytic bicarbonate (aqueous-CO2) reduction and xylose reforming to produce compounds from C—C coupling

Using CO2 (or aqueous-CO2, HCO3−) and biomass as feedstock to produce chemicals under solar irradiation represents a promising approach to achieving the net-zero emission goal. In this study, we employed a highly efficient •H-forming photocatalyst to convert HCO3−, demonstrating the occurrence of CC coupling to produce C2-species. Under simulated solar illumination, the photocatalytic system consistently reduces HCO3− into acetate through the coupling of •CO2− radicals. Additionally, in the photoreforming of xylose, acetate emerges as the predominant product, likely resulting from the coupling of •CO2− derived from the interaction of formate and •OH. Notably, a C6-compound is generated through CC coupling of radicals originating from HCO3− and xylose. Achieving an overall apparent quantum efficiency of 26% under 420-nm irradiation, our work underscores the feasibility of concurrently photocatalyzing the conversion of CO2 and biomass into chemicals through CC coupling. This study not only highlights the significance of our approach in contributing to the net-zero emission goal but also emphasizes the novelty of achieving concurrent photocatalytic conversion.

Gradient‐Tuned VO4 Vacancies in BiVO4 Photoanode for Boosting Bulk Hole Transport and Oxygen Evolution Reaction Performance

AbstractAlthough bismuth vanadate (BiVO4) photoanode has been widely used, the solar‐driven oxygen evolution reaction (OER) performance is constrained due to the substantial bulk recombination and poor mobility of charge carriers. Herein, a facile solvothermal post‐treatment approach that employs N,N‐dimethylformamide (DMF) is developed to induce a VO4 vacancy gradient from bulk to surface of BiVO4 film, which not only improves the charge diffusion but also establishes an advantageous upward band gradient to promote the bulk hole transport. Under Air Mass 1.5 Global (AM1.5G) simulated solar illumination, the optimized BiVO4 photoanode with a VO4 vacancy gradient (denoted as B(VO)1‐δ) exhibits excellent OER performance with a charge separation efficiency of 74.4% at 1.23 V versus reversible hydrogen electrode (RHE) and incident‐photon‐to‐current conversion efficiency of 30.7% at 445 nm, 1.2 and 1.4 times higher than that of the pristine BiVO4, respectively. After loading nickel‐iron hydroxyl oxide (NiFeOOH) as a cocatalyst, the photocurrent density of B(VO)1‐δ escalates to 5.92 mA cm−2 in a hole scavenger (Na2SO3) solution and 5.07 mA cm−2 in a potassium borate buffer solution at 1.23 V versus RHE, far superior to the pristine BiVO4. This work highlights that the gradient‐tuned VO4 vacancies can effectively modulate the bulk band structure and charge transfer in BiVO4 photoanode, providing a new strategy for boosting solar water splitting performance.