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

A facile template-assisted approach is proposed for the construction of a hollow Cr 2 O 3 catalyst with a small size and ultrathin shell. The as-prepared catalyst displays excellent activity toward nitrogen reduction for ammonia production. As a fascinating alternative to the energy-intensive Haber-Bosch process, the electrochemically-driven N 2 reduction reaction (NRR) utilizing the N 2 and H 2 O for the production of NH 3 has received enormous attention. The development and preparation of promising electrocatalysts are requisite to realize an efficient N 2 conversion for NH 3 production. In this research, we propose a template-assisted strategy to construct the hollow electrocatalyst with controllable morphology. As a paradigm, the hollow Cr 2 O 3 nanocatalyst with a uniform size (∼170 nm), small cavity and ultrathin shell (∼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 NH 3 production in ambient condition. In the neutral electrolyte of 0.1 mol·L −1 Na 2 SO 4 , an impressive electrocatalytic performance with the NH 3 generation rate of 2.72 μg·h −1 ·cm −2 and a high FE of 5.31% is acquired respectively at −0.85 V with the hollow Cr 2 O 3 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).