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.