Constructing ultrafine monodispersed Co2P/(0.59-Cu3P) on Cu doped CoZn-ZIF derived porous N-doped carbon for highly efficient dehydrogenation of ammonia borane

Rational construction of highly dispersed, small size, and low cost catalysts for release of hydrogen from ammonia borane (AB) is regarded as a prospective approach for promoting the development of upcoming hydrogen economy. However, the high price and scarcity of precious metal catalysts impose restrictions on their large-scale application. To this end, with the aid of a Cu doped CoZn-zeolitic imidazolate frameworks (ZIFs) template strategy, we successfully construct ultrafine monodispersed Co2P/(0.59-Cu3P) on CoZn-ZIF derived porous N-doped carbon (Co2P/(0.59-Cu3P)-NC) as an efficient non-noble-metal catalyst. Specifically, Co and Cu atoms can be geometrically separated to high degree due to the presence of Zn in the CuCoZn-ZIF precursor, and evaporation of Zn during pyrolysis can generate porous structure with the framework well maintained. The results show that porous Co2P/(0.59-Cu3P)-NC bimetallic phosphide exhibits large specific surface area, hierarchical pore structure, and well-exposed active sites. Based on the kinetics analyses and ion effects, the catalyst has achieved an unprecedentedly high total turnover frequency (TOF) of 798 molH2⋅molcat−1⋅min−1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text{mol}_{\rm{H}_{2}}\cdot\text{mol}_{\text{cat}}^{-1}\cdot\text{min}^{-1}$$\end{document} in 0.4 M NaOH solution at 298 K, which surpasses all the ever-reported transition-metal phosphides catalysts for hydrogen generation from AB. Experiments and theoretical studies confirm that the highly porous structure of the support, the ultrafine and high dispersion of nanoparticles, and the N/P doping and their synergistic effects (e.g., M-P, M-N, N-C, M-M’, and M-support) jointly induce strong electron transfer, which can reduce the reaction energy barrier and enhance their interaction with AB, thus correspondingly obtaining excellent catalytic performance. The mechanism and strategy presented in this work pave an avenue for the design of non-noble metal catalyst for hydrogen energy system.