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In order to respond to the call for low emissions and low energy consumption, photoelectrochemical (PEC) ammonia synthesis is used to replace the Haber-Bosch method of nitrogen reduction, and highly efficient photoelectrocatalysts were used to reduce the reaction energy barrier. In this paper, the interlayer MgO and base BiVO 4 were successfully compounded by a simple electrodeposition method, and the spinel MCo 2 O 4 (M=Zn, Mn) was compounded on MgO/BiVO 4 by a hydrothermal method, forming a sandwich structure of MCo 2 O 4 /MgO/BiVO 4 (M=Zn, Mn). The research shows that the sandwich structure constructed by MgO as the intermediate layer can reduce the excessive surface defects of photocatalyst, effectively reduce the recombination of photogenerated charge, promote the directional migration and separation of photogenerated charge, and improve the photocurrent density and photoelectric conversion efficiency. MCo 2 O 4 (M=Zn, Mn) is a nitrogen reduction cocatalyst, which forms a heterojunction with n-type BiVO 4 and inhibits the recombination of photogenerated electrons. The synergistic effect of MCo 2 O 4 (M=Zn, Mn) and MgO accelerates the surface charge transfer efficiency and enhances the photoelectricity ammonia synthesis efficiency. The PEC ammonia synthesis efficiency reached more than 30 µmol h−1 g−1 cat , and the Faradaic efficiency(FE) is over 30%. [Display omitted] • The sandwich structure photoelectrocatalyst MCo 2 O 4 /MgO/BiVO 4 (M=Zn, Mn) was successfully prepared. • MgO acts as an intermediate layer to accelerate electron transport. • MCo 2 O 4 /MgO/BiVO 4 (M=Zn, Mn) PEC synthesis of ammonia is greatly improved. [ABSTRACT FROM AUTHOR]

Ammonia synthesized by nitrogen reduction is the most promising new energy material. Photoelectrocatalytic (PEC) nitrogen reduction reaction (NRR) occurs under ambient conditions and is the optimal alternative to the energy-intensive Haber-Bosch method. Here, we report the one-step reaction synthesis of Ti–WO 3 /SrWO 4 as a photocathode for ammonia synthesis. First-principles calculations demonstrate that Ti doping can afford nitrogen-adsorption sites, and Ti3+ undergoes chemical adsorption and becomes a nitrogen-activation site by providing electrons to nitrogen. Under light irradiation, the photogenerated electrons are captured by Ti4+; this is conducive to the activation and regeneration of Ti3+, thus forming a nitrogen fixation cycle and improving the nitrogen fixation yield. At − 0.5 V vs. RHE, the ammonia synthesis efficiency reaches 11.17 μg h-1 cm-2, which is four times that of SrWO 4. Furthermore, the high stability and N-gas sensitivity of Ti–WO 3 /SrWO 4 in the NRR indicate that it can be used as an efficient and stable photoelectrocatalyst for ammonia synthesis. [Display omitted] • SrWO 4 firstly utilized as an effective photoelectrocatalyst for N 2 fixation. • Ti-WO 3 /SrWO 4 was synthesized by a one-step reaction based on H 2 WO 4. • N 2 is more easily adsorbed on Ti to facilitate the NRR reaction. • Ti-WO 3 /SrWO 4 PEC synthesis of ammonia is greatly improved. [ABSTRACT FROM AUTHOR]

The inactive macromolecular substances would result in the membrane fouling and reduce the membrane flux in treating traditional Chinese medicine wastewater. Here, we report a novel photocatalytic membrane and utilize aloe-emodin (AE) as electron shuttle synergistically doped into Cu-FeOOH solid solution, then support the photocatalyst AE/Cu-FeOOH on PVDF membrane, which can effectively degrade tannic (95.69 %, 60 min). Furthermore, even after 6 hours of tannic solution filtration, the membrane maintains a high flux of 517 L m−2 h−1 bar−1. Combined with various spectral and photoelectric performance tests confirmed that AE/Cu-FeOOH-PVDF possesses high separation and transfer efficiency of photogenerated carriers. Meanwhile DFT calculation showed that the composite has better adsorption properties and H 2 O 2 activation ability. AE provided e− to Cu-FeOOH, which accelerated the redox reaction process of Fe and Cu ions and produced more stable active free radicals to degrade tannic. This study provides a more environmentally friendly approach for utilizing photocatalytic membranes in the treatment of traditional Chinese medicine wastewater. [Display omitted] • Electron shuttle medium AE doped Cu-FeOOH solid solution improved the conversion efficiency of Fe3+ to Fe2+. • AE/Cu-FeOOH-PVDF/H 2 O 2 effectively degraded tannin in complex Chinese medicine wastewater environment. • The mechanism of H 2 O 2 activation, ROS generation and tannin decomposition were elucidated. • It offers a fresh perspective of photocatalytic membranes in the treatment of wastewater from traditional Chinese medicine. [ABSTRACT FROM AUTHOR]