Controllable synthesis of a hollow Cr₂O₃ electrocatalyst for enhanced nitrogen reduction toward ammonia synthesis

As a fascinating alternative to the energy-intensive Haber-Bosch process, the electrochemically-driven N-2 reduction reaction (NRR) utilizing the N-2 and H2O for the production of NH3 has received enormous attention. The development and preparation of promising electrocatalysts are requisite to realize an efficient N-2 conversion for NH3 production. In this research, we propose a template-assisted strategy to construct the hollow electrocatalyst with controllable morphology. As a paradigm, the hollow Cr2O3 nanocatalyst with a uniform size (similar to 170 nm), small cavity and ultrathin shell (similar to 15 nm) is successfully fabricated with this strategy. This promising hollow structure is favourable to trap N-2 into the cavity, provides abundant active sites to accelerate the three-phase interactions, and facilitates the reactant transfer across the shell. Attributed to these synergetic effects, the designed catalyst displays an outstanding behaviour in N-2 fixation for NH3 production in ambient condition. In the neutral electrolyte of 0.1 mol.L-1 Na2SO4, an impressive electrocatalytic performance with the NH3 generation rate of 2.72 mu g.h(-1)center dot cm(-2) and a high FE of 5.31% is acquired respectively at 0.85 V with the hollow Cr2O3 catalyst. Inspired by this work, it is highly expected that this approach could be applied as a universal strategy and extended to fabricating other promising electrocatalysts for realizing highly efficient nitrogen reduction reaction (NRR). (C) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.