Rational design and modulation strategies of Mo-based electrocatalysts and photo/electrocatalysts towards nitrogen reduction to ammonia (NH3)

As a promising strategy of free energy storage carrier, mainly ammonia (NH3) is produced through the Haber-Bosch process, having extensive requirement of the energy along with the emission of greenhouse gases. However, as a potential Haber-Bosch replacement, the advancement in the photo/electrocatalytic nitrogen reduction process (NRR) is being investigated as a zero-emission electrocatalytic approach by providing alternative routes to achieve green NH3 synthesis. The low selectivity, limited N2 adsorption, and low production rate are major drawbacks. The Mo-based electrocatalysts, which are positioned at the top of the NRR volcano diagram among all metal species, possess the strong capability to catalyze the NRR as an efficient non-noble metal-based material effectively, that indeed required a limiting potential of about 0.5 V for NH3 production on the flat (1 1 0) Mo surface. The current review is designed to compile the latest progress in catalytic NRR. The processes are described, as well as a computational screening of heterogeneous catalysts along with a logical design of the electrochemical system. Furthermore, the modification strategies including defects/vacancy, alloying and interfacial structures, as well as morphological fine structural tuning are presented here as novel Mo-based photo/electrocatalysts for NRR application. Finally, the present challenges and potential for catalyzing NRR are discussed