Millions of families around the world remain vulnerable to water scarcity and have no access to drinking water. Advanced oxidation processes (AOPs) are an effective way towards water purification with qualified reactive oxygen species (ROSs) while are impeded by the high-cost and tedious process in either input of consumable reagent, production of ROSs, and the pre-treatment of supporting electrolyte. Herein, we couple solar light-assisted H2O2 production from water and photo-Fenton-like reactions into a self-cyclable system by using an artificial leaf, achieving an unassisted H2O2 production rate of 0.77 μmol/(min·cm2) under 1 Sun AM 1.5 illumination. Furthermore, a large (70 cm2) artificial leaf was used for an unassisted solar-driven bicarbonate-activated hydrogen peroxide (BAP) system with recycled catalysts for real-time wastewater purification with requirements for only water, oxygen and sunlight. This demonstration highlights the feasibility and scalability of photoelectrochemical technology for decentralized environmental governance applications from laboratory benchtops to industry.

Photoelectrochemical water splitting into H2 and H2O2 has received increasing attention but suffers from uncontrollable selectivity for water oxidative H2O2 production and low solar conversion efficiency. Herein, we present a N2-treated surface oxygen-vacancy-enriched BiVO4 photoanode (N–Ovac–BVO), which tunes the surface wettability of BVO toward a kinetics-controlled H2O2 production process as well as offers higher charge separation efficiency. As a result, the average Faradaic efficiency (FE) reaches 73.8% from 0.6 to 1.9 V vs RHE with the best FE of 81.2%, up to 4 times higher than that of the BVO photoanode. The H2O2 concentration can accumulate to 4.58 × 10–4 M at 1.6 V vs RHE in 2 h, and the corresponding production rate reaches 11.45 μmol·h–1. This work reveals the importance of the photoanode surface microenvironment and provides effective guidance for photoanode design toward the regulation of competing reactions in an aqueous solution.

Bismuth vanadate (BiVO 4 ), with a bandgap of ≈2.4 eV, can harvest light in the waveband below 520 nm and thus has a theoretical photocurrent density of ≈7.5 mA cm −2 under one sun illumination. However, the short hole-diffusion length (<70 nm) of BiVO 4 is an intrinsic limitation that leads to poor charge separation efficiency. Therefore, considerable efforts have been devoted to addressing this issue in recent decades. [11][12][13][14][15] To date, the porous BiVO 4 (P-BiVO 4 ) film reported by Kim and Choi, which comprises several tens or hundreds of nanometers of particles that can remarkably reduce the hole-diffusion distance, has been regarded as a promising thin-film model for PEC conversion. [16] In recent years, research on the PEC performance of the P-BiVO 4 film has undergone a spur of activity, aided by various successful strategies, including vacancy engineering [17][18][19][20][21][22] and cocatalyst loading, [23][24][25][26] which resulted in a charge separation efficiency of up to 90%. However, P-BiVO 4 films generally present poor light absorbability compared to BiVO 4 films composed of micrometer-sized particles. It is well-known that multiple optical phenomena, including reflection, scattering, and transmission, occur simultaneously when incident photons interact with the photoelectrode and together determine the light absorbability of the photoelectrode. Although a porous structure reduces the specular reflection, the scattering effect of a porous structure is The photo-electrochemical (PEC) oxidation of glycerol (GLY) to high-valueadded dihydroxyacetone (DHA) can be achieved over a BiVO 4 photoanode, while the PEC performance of most BiVO 4 photoanodes is impeded due to the upper limits of the photocurrent density. Here, an enhanced Mie scattering effect of the well-documented porous BiVO 4 photoanode is obtained with less effort by a simple annealing process, which significantly reduces the reflectivity to near zero. The great light absorbability increases the basic photocurrent density by 1.77 times. The selective oxidation of GLY over the BiVO 4 photoanode results in a photocurrent density of 6.04 mA cm −2 and a DHA production rate of 325.2 mmol m −2 h −1 that exceeds all reported values. This work addresses the poor ability of nanostructured BiVO 4 to harvest light, paving the way for further improvements in charge transport and transfer to realize highly efficient PEC conversion.

a thermodynamically favorable 4-electron oxygen evolution reaction (OER), as shown in Equations (1) and (2)

Water oxidation reaction leaves room to be improved in the development of various solar fuel productions, because of the kinetically sluggish 4‐electron transfer process of oxygen evolution reaction. In this work, we realize reactive oxygen species (ROS), H2O2 and OH⋅, formations by water oxidation with total Faraday efficiencies of more than 90 % by using inter‐facet edge (IFE) rich WO3 arrays in an electrolyte containing CO32−. Our results demonstrate that the IFE favors the adsorption of CO32− while reducing the adsorption energy of OH⋅, as well as suppresses surface hole accumulation by direct 1‐electron and indirect 2‐electron transfer pathways. Finally, we present selective oxidation of benzyl alcohol by in situ using the formed OH⋅, which delivers a benzaldehyde production rate of ≈768 μmol h−1 with near 100 % selectivity. This work offers a promising approach to tune or control the oxidation reaction in an aqueous solar fuel system towards high efficiency and value‐added product.