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Bismuth vanadate (BiVO 4 ) has been widely investigated as a photocatalyst or photoanode for solar water splitting, but its activity is hindered by inefficient cocatalysts and limited understanding of the underlying mechanism. Here we demonstrate significantly enhanced water oxidation on the particulate BiVO 4 photocatalyst via in situ facet-selective photodeposition of dual-cocatalysts that exist separately as metallic Ir nanoparticles and nanocomposite of FeOOH and CoOOH (denoted as FeCoO x ), as revealed by advanced techniques. The mechanism of water oxidation promoted by the dual-cocatalysts is experimentally and theoretically unraveled, and mainly ascribed to the synergistic effect of the spatially separated dual-cocatalysts (Ir, FeCoO x ) on both interface charge separation and surface catalysis. Combined with the H 2 -evolving photocatalysts, we finally construct a Z-scheme overall water splitting system using [Fe(CN) 6 ] 3−/4− as the redox mediator, whose apparent quantum efficiency at 420 nm and solar-to-hydrogen conversion efficiency are optimized to be 12.3% and 0.6%, respectively. Artificial photosynthesis offers an integrated means to convert light to fuel, but efficiencies are often low. Here, authors report a Z-scheme system utilizing Ir and FeCoO x co-catalysts to enhance charge separation on BiVO 4 facets that achieves high quantum efficiencies for overall water splitting.

Photocatalytic hydrogen peroxide formation is an advancing field with various approaches motivated by the promise of a green oxidant and energy carrier for a sustainable future. An assessment on quantification methods, sacrificial agents and best practices is provided to avoid false positives and support progress in the field.

Sunlight is our most abundant, clean and inexhaustible energy source. However, its diffuse and intermittent nature makes it difficult to use directly, suggesting that we should instead store this energy. One of the most attractive avenues for this involves using solar energy to split H 2 O and afford H 2 through artificial photosynthesis, the practical realization of which requires low-cost, robust photocatalysts. Colloidal quantum dots (QDs) of IIB–VIA semiconductors appear to be an ideal material from which to construct highly efficient photocatalysts for H 2 photogeneration. In this Review, we highlight recent developments in QD-based artificial photosynthetic systems for H 2 evolution using sacrificial reagents. These case studies allow us to introduce strategies — including size optimization, structural modification and surface design — to increase the H 2 evolution activities of QD-based artificial photosystems. Finally, we describe photocatalytic biomass reforming and unassisted photoelectrochemical H 2 O splitting — two new pathways that could make QD-based solar-to-fuel conversion practically viable and cost-effective in the near future. Semiconducting quantum dots (QDs) can serve as light-absorbing components in efficient artificial photosynthetic systems for H 2 evolution. This Review describes how we can optimize QDs for H 2 evolution using sacrificial reductants, before moving on to sustainable strategies for the photolysis of biomass or H 2 O.

In nature, plants convert solar energy into chemical energy via water oxidation. Inspired by natural photosynthesis, artificial photosynthesis has been gaining increasing interest in the field of sustainability/green science and technology as a non-natural and thermodynamically endergonic (Δ G ° > 0, uphill) solar-energy-driven reaction that uses water as an electron donor and a source material. Among the artificial-photosynthesis processes, inorganic-synthesis reactions via water oxidation, including water splitting and CO 2 -to-fuel conversion, have been attracting much attention. In contrast, the synthesis of high-value functionalized organic compounds via artificial photosynthesis, which we have termed artificial photosynthesis directed toward organic synthesis (APOS), remains a great challenge. Herein, we report a synthetically pioneering and meaningful strategy of APOS, where the carbohydroxylation of C = C double bonds is accomplished via a three-component coupling with H 2 evolution using dual functions of semiconductor photocatalysts, i.e., silver-loaded titanium dioxide (Ag/TiO 2 ) and rhodium–chromium–cobalt-loaded aluminum-doped strontium titanate (RhCrCo/SrTiO 3 :Al). Emulating the concept of natural photosynthesis has long been a focus of chemists in an effort to harness solar light as an energy source using water as an electron donor and a source material. Here, the authors present an artificial photosynthetic system that can functionalize styrenes via C–H activation and water splitting.

Organic semiconductors hold promise to enable scalable, low-cost and high-performance artificial photosynthesis. However, the performance of systems based on organic semiconductors for light-driven water oxidation have remained poor compared with inorganic semiconductors. Herein, we demonstrate an all-polymer bulk heterojunction organic semiconductor photoanode for solar water oxidation. By engineering the photoanode interlayers we gain important insights into critical factors (surface roughness and charge extraction efficiency) to increase the operational stability, which reaches above 3 h with a 1-Sun photocurrent density, J ph , of >3 mA cm −2 at 1.23 V versus the reversible hydrogen electrode for the sacrificial oxidation of Na 2 SO 3 at pH 9. Optimizing the coupling to an oxygen evolution catalyst yields O 2 production with J ph  > 2 mA cm −2 at 1.23 V versus the reversible hydrogen electrode (100% Faradaic efficiency and a quantum efficiency up to 27% with 610 nm illumination), demonstrating improved stability (≥1 mA cm −2 for over 30 min of continuous operation) compared with previous organic photoanodes. Conductive polymers are attractive materials for the construction of photoelectrodes in the context of artificial photosynthesis, although their performance is still limited. Now, an organic semiconductor photoanode for water oxidation is presented, which provides high photocurrent density for over 30 minutes.

Artificial photosynthesis is a desirable critical technology for the conversion of CO 2 and H 2 O, which are abundant raw materials, into fuels and chemical feedstocks. Similar to plant photosynthesis, artificial photosynthesis can produce CO, CH 3 OH, CH 4 , and preferably higher hydrocarbons from CO 2 using H 2 O as an electron donor and solar light. At present, only insufficient amounts of CO 2 -reduction products such as CO, CH 3 OH, and CH 4 have been obtained using such a photocatalytic and photoelectrochemical conversion process. Here, we demonstrate that photocatalytic CO 2 conversion with a Ag@Cr-decorated mixture of CaGa 4 O 7 -loaded Ga 2 O 3 and the CaO photocatalyst leads to a satisfactory CO formation rate (>835 µmol h −1 ) and excellent selectivity toward CO evolution (95%), with O 2 as the stoichiometric oxidation product of H 2 O. Our photocatalytic system can convert CO 2 gas into CO at >1% CO 2 conversion (>11531 ppm CO) at ambient temperatures and pressures. Photocatalytic CO 2 reduction requires catalysts that are both active and selective. Here, a mixture of CaGa 4 O 7 -loaded Ga 2 O 3 and CaO, decorated with Ag@Cr core-shell particles, delivers over 835 µmol h −1 of CO at >95 % selectivity.

Discerning the precise mechanisms of photocatalytic energy conversion has long been a challenge. A computational multiscale approach reveals insights into the reaction pathways and rate-limiting steps of the oxygen evolution reaction, the bottleneck for water splitting on TiO 2 surfaces.