Amorphous MnCO₃/C Double Layers Decorated on BiVO₄ Photoelectrodes to Boost Nitrogen Reduction

NH₃ is mainly obtained by the Haber-Bosch method in the process of industrial production, which is not only accompanied by huge energy consumption but also environmental pollution. The reduction of N₂ to NH₃ under mild conditions is an important breakthrough to solve the current energy and environmental problems, so the preparation of catalysts that can effectively promote the reduction of N₂ is a crucial step. In this work, BiVO₄ decorated with amorphous MnCO₃/C double layers has been successfully synthesized by a one-step method for the first time. The C and MnCO₃ have been formed as ultrathin film, which enables the establishment of a uniform and tight interface with BiVO₄. The temperature-programmed desorption of N₂ (N₂-TPD) spectra confirmed that the MnCO₃/C could endow BiVO₄ with a drastic enhancement of the chemical absorption ability of a N₂ molecule compared with the pristine BiVO₄. Meanwhile, the method of isotope labeling proved that the catalyst exhibited excellent selectivity for the photocatalytic nitrogen reduction reaction (NRR). The production rate of NH₃ up to 2.426 mmol m^-2 h^-1 has been achieved over the BiVO₄/MnCO₃/C, which is almost 8 times that of pristine BiVO₄. The promoted production rate of NH₃ over BiVO₄/MnCO₃/C could be mainly attributed to the cooperative process between MnCO₃ and C amorphous layers. Therefore, this work could provide an alternative insight to understand the NRR process based on the model of a hierarchical amorphous structure.