Phase manipulating toward Ni catalysts via lattice nitrogen endows high energy density hydrogen gas battery

Metastable structures commonly generate unique catalytic effects. However, it is challenging to prepare due to thermodynamic limitations. Here, we first propose a nitrogen insertion strategy for Ni phase manipulating in alkaline hydrogen oxidation reaction (HOR). With the incremental lattice nitrogen, face centered cubic (fcc), bi-mixed fcc and N-induced an unconventional hexagonal close packed (N-u-hcp), tri-mixed fcc-Ni/N-u-hcp-Ni/Ni3N and Ni3N phase evolves successively, with corresponding volcanic HOR activities. Specifically, the biphasic fcc-Ni/N-u-hcp-Ni shows highest activity of 67 A g−1. Theoretical calculations show that lattice nitrogen reduce the formation energy of biphasic Ni, and this biphasic structure could provide electron rich interface to optimize the adsorption of H* and OH*. As a proof-of-concept for Ni-H2 battery, the gas diffusion electrode prepared with this biphasic Ni catalyst achieves an 8 Ah Ni-H2 battery with 163 Wh kg−1. This study provides an inspiration for the controllable synthesis of metastable nano-catalysts and demonstrates the efficient catalysis in practical hydrogen energy applications.