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Circumventing the conventional two-electron oxygen reduction pathway remains a great problem in enhancing the efficiency of H 2 O 2 photosynthesis. A promising approach to achieve outstanding photocatalytic activity involves the utilization of redox intermediates. Here, we engineer a polyimide aerogel photocatalyst with photoreductive carbonyl groups for non-sacrificial H 2 O 2 production. Under photoexcitation, carbonyl groups on the photocatalyst surface are reduced, forming an anion radical intermediate. The produced intermediate is oxidized by O 2 to produce H 2 O 2 and subsequently restores the carbonyl group. The high catalytic efficiency is ascribed to a photocatalytic redox cycle mediated by the radical anion, which not only promotes oxygen adsorption but also lowers the energy barrier of O 2 reduction reaction for H 2 O 2 generation. An apparent quantum yield of 14.28% at 420 ± 10 nm with a solar-to-chemical conversion efficiency of 0.92% is achieved. Moreover, we demonstrate that a mere 0.5 m 2 self-supported polyimide aerogel exposed to natural sunlight for 6 h yields significant H 2 O 2 production of 34.3 mmol m −2 . The photocatalytic redox cycle mediated by the anion radical intermediate promotes oxygen adsorption and lowers the energy barrier of O2 reduction reaction, thereby significantly improving the efficiency of H2O2 photosynthesis.

Hydrogen peroxide (H 2 O 2 ) is an important industrial chemical and also a possible energy carrier. Photocatalytic synthesis of H 2 O 2 is an attractive alternative to the anthraquinone process, but current catalyst systems suffer from many problems including: a limited sunlight wavelength response, the need for sacrificial reagents and insufficient activity. Here we report self-assembled tetrakis(4-carboxyphenyl)porphyrin supramolecular photocatalysts that produce H 2 O 2 from only H 2 O and O 2 and with a quantum efficiency of 14.9% at 420 nm and 1.1% at 940 nm. The catalyst achieves a solar-to-chemical conversion efficiency of 1.2% at 328 K when irradiated and heated with simulated sunlight. Our results suggest that photogenerated electrons and holes contribute to H 2 O 2 production by reacting on different active sites including pyrrole N–H ring and carboxyl groups. In particular, we propose a hole-induced H 2 O 2 production process, which involves the photoconversion of -COOH to -CO 3 H groups on the catalyst, followed by thermal decomposition. Photocatalytic synthesis of H 2 O 2 is an attractive route to this important chemical and potential energy carrier, but improvements in performance and operation without sacrificial agents are needed. Here the authors report a porphyrin-based photocatalyst with promising performance for H 2 O 2 production from only H 2 O and O 2 .

Photocatalytic water splitting into hydrogen and oxygen is a method to directly convert light energy into storable chemical energy, and has received considerable attention for use in large-scale solar energy utilization. Particulate semiconductors are generally used as photocatalysts, and semiconductor properties such as bandgap, band positions, and photocarrier mobility can heavily impact photocatalytic performance. The design of active photocatalysts has been performed with the consideration of such semiconductor properties. Photocatalysts have a catalytic aspect in addition to a semiconductor one. The ability to control surface redox reactions in order to efficiently produce targeted reactants is also important for photocatalysts. Over the past few decades, various photocatalysts for water splitting have been developed, and a recent main concern has been the development of visible-light sensitive photocatalysts for water splitting. This review introduces the study of water-splitting photocatalysts, with a focus on recent progress in visible-light induced overall water splitting on oxynitride photocatalysts. Various strategies for designing efficient photocatalysts for water splitting are also discussed herein.

Conversion of methane into value‐added chemicals is of significance for methane utilization and industrial demand of primary chemical products. The barrier associated with the nonpolar structure of methane and the high bond energy C–H bond (4.57 eV) makes it difficult to realize methane conversion and activation under mild conditions. The photothermal synergetic strategy by combining photon energy and thermo energy provides an advanced philosophy to achieve efficient methane conversion. In this review, we overview the current pioneering studies of photothermal methane indirect conversion and present the methane direct conversion by the way of photocatalysis and thermocatalysis to provide a fundamental understanding of methane activation. Finally, we end this review with a discussion on the remaining challenges and perspectives of methane direct conversion over single‐atom catalysts via photothermal synergetic strategy. Methane conversion into value‐added chemicals is highly important for producing industrially demanded primary chemical products but still very challenging. The recently developed photothermal synergetic strategy by coupling photo‐ and thermo‐catalytic processes provides an advanced methodology to boost methane conversion. In this review, we summarize the pioneering research on photothermal methane direct and indirect conversion to provide a fundamental understanding of methane activation and conversion.

Rationally constructing atom‐precise active sites is highly important to promote their catalytic performance but still challenging. Herein, this work designs and constructs ZSM‐5 supported Cu and Ag dual single atoms as a proof‐of‐concept catalyst (Ag 1 −Cu 1 /ZSM‐5 hetero‐SAC (single‐atom catalyst)) to boost direct oxidation of methane (DOM) by H 2 O 2 . The Ag 1 −Cu 1 /ZSM‐5 hetero‐SAC synthesized via a modified co‐adsorption strategy yields a methanol productivity of 20,115 µmol g cat −1 with 81% selectivity at 70 °C within 30 min, which surpasses most of the state‐of‐the‐art noble metal catalysts. The characterization results prove that the synergistic interaction between silver and copper facilitates the formation of highly reactive surface hydroxyl species to activate the C−H bond as well as the activity, selectivity, and stability of DOM compared with SACs, which is the key to the enhanced catalytic performance. This work believes the atomic‐level design strategy on dual‐single‐atom active sites should pave the way to designing advanced catalysts for methane conversion.

Direct oxidation of methane (DOM) into high-value C2+ products using molecular oxygen (O 2 ) is essential for the sustainable production of clean energy and bulk chemicals, but is still challenging due to the difficult C-H activation and uncontrollable C-C coupling process. Herein, we design and construct the Fe-(μ-O)-Zn dual-atom sites by supporting Fe and Zn atoms on ZSM-5 (Fe 1 -Zn 1 /ZSM-5), which achieves the DOM by O 2 to acetic acid under ambient temperature and pressure. The Fe-(μ-O)-Zn dual-atom sites yield an acetic acid productivity of 3006 μmol•g cat −1 •h −1 with 86.8% selectivity (total C2+ products selectivity of 93.0%) for at least 20 hours at 25 o C and atmospheric pressure. The mutual electronic modulation between Fe and Zn shifts the d -band center of Fe 3 d in Fe-(μ-O)-Zn dual-atom sites upwards, which promotes the formation and stabilization of highly reactive Fe=O species through O 2 photodissociation and thereby enhances the C-H bond activation of CH 4 . The Fe-(μ-O)-Zn dual-atom reaction sites (spatial distance of 2.7 Å) boost the C-C coupling of key CH 3 and HCHO intermediate species, which steadily produce acetic acid and other C2+ oxygenates. This work would broaden the avenue towards the sustainable conversion of methane to value-added C2+ products under ambient temperature and pressure. Direct methane oxidation to C2+ with O 2 is impeded by tough C–H activation and uncontrolled coupling. Here, Fe-(μ-O)-Zn dual-atom sites on ZSM-5 enable efficient photocatalytic acetic acid production at ambient temperature and pressure.

Hollow carbon nitride nanosphere (HCNS) was synthesized via the hard template method to improve the fluorescence characteristics, drug delivery ability, and photocatalytic activity. Blue fluorescent HCNS was utilized as a quenching agent and an internal reference to combine with Cy5-labelled aptamer (Cy5-Apt), resulting in an off-on fluorescence aptasensing method for the detection of Salmonella typhimurium (S. typhimurium). Under optimum conditions, this fluorescence assay presented a linear range from 30 to 3 × 104 CFU mL−1 with a detection limit of 13 CFU mL−1. In addition, HCNS was also used as a drug carrier to load chloramphenicol (Cap) molecules. The Cap-loading amount of HCNS could reach 550 μg mg−1 within 24 h, whereas the corresponding Cap-release amount is 302.5 μg mg−1 under acidic and irradiation conditions. The integration of photocatalyst with antibiotic could endow HCNS-Cap with better disinfection performance. The bactericidal efficiency of HCNS-Cap (95.0%) against S. typhimurium within 12 h was better than those of HCNS (85.1%) and Cap (72.9%). In addition, selective disinfection of S. typhimurium was further realized by decorating aptamer. Within 4 h, almost all S. Typhimurium were inactivated by HCNS-Cap-Apt, whereas only 13.3% and 48.2% of Staphylococcus aureus and Escherichia coli cells were killed, respectively. Therefore, HCNS is a promising bio-platform for aptamer-based fluorescence detection and selective disinfection of S. typhimurium.

Circumventing the conventional two-electron oxygen reduction pathway remains a great problem in enhancing the efficiency of H O photosynthesis. A promising approach to achieve outstanding photocatalytic activity involves the utilization of redox intermediates. Here, we engineer a polyimide aerogel photocatalyst with photoreductive carbonyl groups for non-sacrificial H O production. Under photoexcitation, carbonyl groups on the photocatalyst surface are reduced, forming an anion radical intermediate. The produced intermediate is oxidized by O to produce H O and subsequently restores the carbonyl group. The high catalytic efficiency is ascribed to a photocatalytic redox cycle mediated by the radical anion, which not only promotes oxygen adsorption but also lowers the energy barrier of O reduction reaction for H O generation. An apparent quantum yield of 14.28% at 420 ± 10 nm with a solar-to-chemical conversion efficiency of 0.92% is achieved. Moreover, we demonstrate that a mere 0.5 m self-supported polyimide aerogel exposed to natural sunlight for 6 h yields significant H O production of 34.3 mmol m .

Direct oxidation of methane (DOM) into high-value C2+ products using molecular oxygen (O ) is essential for the sustainable production of clean energy and bulk chemicals, but is still challenging due to the difficult C-H activation and uncontrollable C-C coupling process. Herein, we design and construct the Fe-(μ-O)-Zn dual-atom sites by supporting Fe and Zn atoms on ZSM-5 (Fe -Zn /ZSM-5), which achieves the DOM by O to acetic acid under ambient temperature and pressure. The Fe-(μ-O)-Zn dual-atom sites yield an acetic acid productivity of 3006 μmol•g •h with 86.8% selectivity (total C2+ products selectivity of 93.0%) for at least 20 hours at 25 C and atmospheric pressure. The mutual electronic modulation between Fe and Zn shifts the d-band center of Fe 3d in Fe-(μ-O)-Zn dual-atom sites upwards, which promotes the formation and stabilization of highly reactive Fe=O species through O photodissociation and thereby enhances the C-H bond activation of CH . The Fe-(μ-O)-Zn dual-atom reaction sites (spatial distance of 2.7 Å) boost the C-C coupling of key CH and HCHO intermediate species, which steadily produce acetic acid and other C2+ oxygenates. This work would broaden the avenue towards the sustainable conversion of methane to value-added C2+ products under ambient temperature and pressure.

Front cover image: Converting methane into industrially important primary chemical products is highly desired but still very challenging since the high barrier of activating the first C‐H bond of methane (4.57 eV) makes it extremely difficult to realize methane efficient activation and selective conversion under mild conditions. In article number 10.1002/cey2.127, Lou and Zhu et al. summarize the recent progress related to the photothermal synergetic strategy boosting the activation and selective conversion of methane to methanol and other high‐value products.