d-Block transition metal-based catalysts for electrocatalytic ammonia synthesis

d-Block transition metals (d-TMs) are considered to be an ideal candidate for electrocatalytic nitrogen reduction reaction (NRR) catalysts because they are easy to be modified. Meanwhile, they possess unfilled valence d orbitals, which are conducive to adsorbing nitrogen (N2), as well as separated d electrons can donate into N2 Consequently, considerable progress of d-TMs in NRR has been acquired in in-depth research. This article reviewed the latest researches on the applications of d-TMs based materials, which were designed and synthesized by different modification strategies to NRR. The NRR mechanisms based on d-TMs catalysts were briefly described. Moreover, the d-TMs based NRR catalysts designed by modification strategies such as surface/interface engineering, crystal facet regulation/amorphization, defect engineering, as well as the construction of bionic site, were summarized in detail and the influence of each modification strategy on NRR performance was analyzed. Finally, this article prospected the development prospects of this field and proposed the problems that need to be paid attention in the future from a series of perspectives, e.g., theoretical calculation model, catalyst modification strategies, electrochemical system, testing and characterization methods, and ammonia (NH3) detection methods, so as to provide references for the design of modified d-TMs based efficient NRR catalysts. © 2021, Chemical Industry Press Co., Ltd. All right reserved.