Highly dispersed Cu atoms in MOF-derived N-doped porous carbon inducing Pt loads for superior oxygen reduction and hydrogen evolution

Abstract

The preparation of oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) catalysts with high activity, stability and low platinum loading has always been the focus of research. The single-atom platinum supported catalyst greatly improves the utilization of platinum, but the catalytic activity and selectivity are greatly affected by the platinum coordination environment, and the preparation of the material is difficult. Doping base metals to adjust the electronic structure of platinum is an effective strategy to improve catalyst performance. In this work, copper-platinum alloy nanoparticles were loaded on N-doped porous carbon via a targeted route guided by highly dispersed Cu atoms derived from MOF. The product C-ZIF-CuPt has high activity and high stability ORR, HER bifunctional catalytic performance, which is better than commercial Pt/C (20 wt%). The Pt activity in C-ZIF-CuPt is 4.4 times (ORR) and 6.7 times (HER) than Pt/C. Spectromicroscopic determinations unveiled that strong interactions between carbon carrier and the CuPt alloys contribute to the overall stabilities. DFT calculations show that Cu doping can increase the d-band center of Pt, reduce the ORR overpotential, and the activation energy barrier to water molecules, which is beneficial to ORR and HER catalysis. Under the same carrier conditions, the performance of sub-nano (single atoms, clusters) platinum-supported catalysts (C-ZIF-Cu-Pt) is inferior to C-ZIF-CuPt. This further shows that platinum alloying can effectively improve the performance of the catalyst.