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Artificial photosynthesis in carbon dioxide (CO2) conversion into value-added chemicals attracts considerable attention but suffers from the low activity induced by sluggish separation of photogenerated carriers and the kinetic bottleneck-induced unsatisfied selectivity. Herein, we prepare a new-style Bi/TiO2 catalyst formed by pinning bismuth clusters on TiO2 nanowires through being confined by pores, which exhibits high activity and selectivity towards photocatalytic production of CH4 from CO2. Boosted charge transfer from TiO2 through Bi to the reactants is revealed via in situ X-ray photon spectroscopy and time-resolved photoluminescence (PL). Further, in situ Fourier transform infrared results confirm that Bi/TiO2 not only overcomes the multi-electron kinetics challenge of CO2 to CH4 via boosting charge transfer, but also facilitates proton production and transfer as well as the intermediates ⋆CHO and ⋆CH3O generation, ultimately achieving the tandem catalysis towards methanation. Theoretical calculation also underlies that the more favorable reaction step from ⋆CO to ⋆CHO on Bi/TiO2 results in CH4 production with higher selectivity. Our work brings new insights into rational design of photocatalysts with high performance and the formation mechanism of CO2 to CH4 for solar energy storage in future. [ABSTRACT FROM AUTHOR]

The intrinsic flexoelectric effect observed in oxide materials often falls below the desired threshold for practical applications. In this work, we demonstrate proton doping in insulating rutile TiO2 crystal as an effective approach to significantly increase flexoelectricity by more than two orders of magnitude. We attribute the noteworthy enhancement of flexoelectricity to the dual impact of proton doping in oxide materials. First, proton doping serves to induce the presence of charge carriers, resulting in the generation of flexoelectric currents. Second, proton doping induces expansion and distortion of the lattice structure, leading to an amplified flexoelectric field when the crystal experiences a strain gradient. The formation of O–H bonding in TiO2 crystal provides another route to break centrosymmetry according to lattice distortion of the TiO2 lattice, resulting in a larger flexoelectric field. In addition, the introduction of proton doping in TiO2 single crystals leads to a substantial increase in photocurrent by effectively flattening the interfacial Schottky junction. This phenomenon results in a three-order of magnitude enhancement of the photocurrent. Our work broadens the horizon of study on dielectric materials through proton doping and may also provide an approach that enables the utilization of dielectric materials in energy conversion applications. [ABSTRACT FROM AUTHOR]

Highly efficient photocathode with onset potential beyond 0.6 V is very desirable in order to construct photoelectrochemical (PEC) device for stand‐alone overall water splitting. In this work, it is reported a nonfullerene PBDB‐T:ITIC bulk heterojunction (BHJ) based photocathode delivering unprecedented positive onset potential of 0.8 V and optimal photocurrent density of −11.7 mA cm−2 at 0 V in pH 1 solution. The yielded high ideal ratiometric power‐saved efficiency (Φsaved,ideal) of 4.1% is a record among the previous organic photocathodes. When the electrolyte pH moves to neutral, the Φsaved,ideal is still to be 3.2%, yet being twice more than the currently reported highest value. Pairing with TiOx, the hole transport layer of CuOx with more efficient charge carrier transportation and hole extraction ability excels MoO3 and NiOx, contributing to the highly efficient solar hydrogen production in both acidic and neutral solutions. Premixing the BHJ blend precursor with an anti‐oxidative agent is proved to be a beneficial strategy to improve the PEC stability by suppressing the photo‐oxidation degradation of organic polymer materials. Subsequently a conceptual PEC cell comprising of tandem CuOx/BHJ/TiOx/Pt photocathode and BiVO4/NiFeOx photoanode with a high solar‐to‐hydrogen efficiency up to 1.1% is fabricated in neutral solution without assistance of extra bias. [ABSTRACT FROM AUTHOR]

The intrinsic flexoelectric effect observed in oxide materials often falls below the desired threshold for practical applications. In this work, we demonstrate proton doping in insulating rutile TiO2 crystal as an effective approach to significantly increase flexoelectricity by more than two orders of magnitude. We attribute the noteworthy enhancement of flexoelectricity to the dual impact of proton doping in oxide materials. First, proton doping serves to induce the presence of charge carriers, resulting in the generation of flexoelectric currents. Second, proton doping induces expansion and distortion of the lattice structure, leading to an amplified flexoelectric field when the crystal experiences a strain gradient. The formation of O–H bonding in TiO2 crystal provides another route to break centrosymmetry according to lattice distortion of the TiO2 lattice, resulting in a larger flexoelectric field. In addition, the introduction of proton doping in TiO2 single crystals leads to a substantial increase in photocurrent by effectively flattening the interfacial Schottky junction. This phenomenon results in a three-order of magnitude enhancement of the photocurrent. Our work broadens the horizon of study on dielectric materials through proton doping and may also provide an approach that enables the utilization of dielectric materials in energy conversion applications. [ABSTRACT FROM AUTHOR]