Nitrogen Doped Carbon Nanosheets Coupled Nickel–Carbon Pyramid Arrays Toward Efficient Evolution of Hydrogen

The implementation of water electrolysis cells to produce hydrogen for practical usage requires highly efficient and cost-effective electrode materials that can replace the exorbitant Pt based catalysts. Herein, the outstanding hydrogen evolution performance of a nonprecious material based electrocatalyst obtained through the pyrolysis of bilayer thin films of metal–organic framework and graphitic carbon nitride supported on a 3D Ni foam is demonstrated. The obtained electrocatalyst exhibits a pyramid structure composed of nickel and carbon, coupled with nitrogen doped carbon nanosheets on the outer layer. It requires a negligible overpotential (≈0 mV) to initiate hydrogen evolution reaction (HER) in alkaline media. The overpotentials needed to deliver current densities of 10 and 100 mA cm⁻² are 8 and 28 mV, respectively. Moreover, the as-prepared electrode also exhibits prominent stability in prolonged constant potential electrolysis of water. Density functional theory calculations reveal the active sites originated from the combination of nitrogen doped carbon nanosheets (N-C) and the encapsulated Ni nanoparticles. Furthermore, the obtained hydrogen electrode is one of the most active catalysts toward HER, even comparable with the benchmarking platinum carbon catalyst. It has the potential to be fabricated and employed as the working electrode for large-scale electrolytic generation of hydrogen from water.