One of the simplest methods for splitting water into H2 and O2 with solar energy entails the use of a particulate-type semiconductor photocatalyst. To harness solar energy efficiently, a new water-splitting photocatalyst that is active over a wider range of the visible spectrum has been developed. In particular, a complex perovskite-type oxynitride, LaMg(x)Ta(1-x)O(1+3x)N(2-3x)(x≥1/3), can be employed for overall water splitting at wavelengths of up to 600 nm. Two effective strategies for overall water splitting were developed. The first entails the compositional fine-tuning of a photocatalyst to adjust the bandgap energy and position by forming a series of LaMg(x)Ta(1-x)O(1+3x)N(2-3x) solid solutions. The second method is based on the surface coating of the photocatalyst with a layer of amorphous oxyhydroxide to control the surface redox reactions. By combining these two strategies, the degradation of the photocatalyst and the reverse reaction could be prevented, resulting in successful overall water splitting.
A two-step photodeposition method is introduced, aiming to construct a p-type Cu2O interlayer between n-type CdS and NiOx cocatalyst. The effect of Cu2O interlayer is supposed to accelerate the hole transfer from CdS.
Abstract CdV 2 O 6 and Cd 2 V 2 O 7 were successfully synthesized by a simple hydrothermal process. The effects of the hydrothermal temperature and pH on the phase transition between CdV 2 O 6 and Cd 2 V 2 O 7 were investigated in detail. That the Cd 2 V 2 O 7 phase could transform into CdV 2 O 6 was attributed to polymerization of vanadate in an acidic environment as the V/O ratio increased as the pH decreased. V 2 O 7 4– was stable in a neutral or alkaline environment at an identical hydrothermal temperature, therefore, the Cd 2 V 2 O 7 phase was obtained after hydrothermal treatment for 24 h. Because the degree of hydrolysis of NH 4 Cl increased with increasing temperature in the solution, the increased temperature accelerated the speed of the pH decrease. Therefore, the hydrothermal temperature played an important part in the phase transition between CdV 2 O 6 and Cd 2 V 2 O 7 . CdV 2 O 6 and Cd 2 V 2 O 7 showed high photocatalytic activity for the degradation of methylene blue under visible‐light irradiation.
Abstract 2D bismuth nanosheets are a promising layered material for formate‐producing via electrocatalytic CO 2 conversion. However, the commercial interest of bismuth nanosheets in CO 2 electroreduction is still rare due to the undesirable current density for formate at moderate operation potentials (about 200 mA mg −1 ) and harsh synthesis conditions (high temperature and/or high pressure). This work reports the preparation of Bi nanosheets with a lateral size in micrometer‐scale via electrochemical cathodic exfoliation in aqueous solution at normal pressure and temperature. As‐prepared Bi LNSs (L indicates large lateral size) possess high Faradaic efficiencies over 90% within a broad potential window from −0.44 to −1.10 V versus RHE and a superior partial current density about 590 mA mg −1 for formate in comparison with state‐of‐the‐art results. Structure analysis, electrochemical results, and density functional theory calculations demonstrate that the increasing tensile lattice strain observed in Bi LNSs leads to less overlap of d orbitals and a narrower d‐band width, which tuning the intermediate binding energies, and therefore promotes the intrinsic activity.
Abstract 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.
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