FeS2/MoS2@RGO hybrid materials derived from polyoxomolybdate-based metal–organic frameworks as high-performance electrocatalyst for ammonia synthesis under ambient conditions

Electrochemical nitrate reduction (NO3-RR) to synthesize ammonia is considered to be a promising strategy to enable artificial nitrogen cycle. Great efforts have been devoted to improving the efficiency and selectivity of the electrocatalysts for NO3-RR. Herein, we demonstrate that tuning the oxygen chemical environment via Ar plasma treatment is an effective approach to improve the NO3-RR activity of Cu2O. Combining synchrotron-based X-ray absorption spectroscopy and other advanced spectroscopy techniques, we find that plasma treatment can effectively promote the formation of oxygen vacancies and hydroxyl groups on Cu2O surface. In-situ diffuse-reflectance infrared Fourier transform spectroscopy and density functional theory calculation further reveal that oxygen vacancies and hydroxyl groups facilitate the adsorption of nitrate and proton transfer on the Cu2O surface, thus leading to improved ammonia selectivity. Our results clarify the critical role of surface oxygen species for NO3-RR and can guide the design of other electrocatalysts via surface engineering. 

Regulating surface oxygen species on copper (I) oxides via plasma treatment for effective reduction of nitrate to ammonia

Defect engineering for high-selection-performance of NO reduction to NH3 over CeO2 (111) surface: A DFT study

Enhanced photocatalytic degradation performance of BiVO4/BiOBr through combining Fermi level alteration and oxygen defect engineering

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.

Qianxiao Zhang

Papers

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

Charge-transfer dynamics at a Ag/Ni-MOF/Cu2O heterostructure in photoelectrochemical NH3 production.

In-situ decoration of unsaturated Cu sites on Cu2O photocathode for boosting nitrogen reduction reaction