Vapor ammonization strategy towards surface-reconstructed and N-modified three-dimensional Cu foam electrocatalyst for efficient alkaline hydrogen production

Development of highly active and stable noble-metal-free electrocatalysts is of great significance for large-scale electrocatalytic hydrogen evolution reaction (HER). Herein, we develop an effective vapor ammonization-electroreduction strategy for fabricating a surface-reconstructed and N-modified three dimensional (3D) Cu foam (SN-CF) cathode for highly efficient alkaline HER. The vapor ammonization is effective to enhance the surface roughness of 3D Cu foam (CF), which is beneficial to enhance the catalytically active surface areas and active site density. Meanwhile, the in situ formation of the surface Cu-N species can effectively regulate the electronic structures of surface active sites. As a result, the thus-obtained SN-CF electrocatalyst exhibits a superior electrocatalytic activity towards HER in 1.0 M KOH solution, and it requires low overpotentials of 188 and 377 mV at a current density of 10 and 100 mA cm(-2), respectively. Moreover, SN-CF also exhibits a good cycling stability (95% after 2000 cycles) and long-term durability for 12 h at a current density of 10 mA cm(-2). This work provides a simple and effective strategy for rationally fabricating highly active HER electrocatalysts by synergistically tuning the surface nano structures and coordination environment of transition metals. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.