As a fascinating alternative to the energy-intensive Haber-Bosch process,the electrochemically-driven N2 reduction reaction (NRR) utilizing the N2 and H2O for the production of NH3 has received enormous attention.The development and preparation of promising electrocatalysts are requisite to realize an effi-cient N2 conversion for NH3 production.In this research,we propose a template-assisted strategy to con-struct the hollow electrocatalyst with controllable morphology.As a paradigm,the hollow Cr2O3 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 N2 into the cavity,pro-vides 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 N2 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 μg·h-1·cm 2 and a high FE of 5.31％ is acquired respectively at-0.85 V with the hollow Cr2O3 cat-alyst.Inspired by this work,it is highly expected that this approach could be applied as a universal strat-egy and extended to fabricating other promising electrocatalysts for realizing highly efficient nitrogen reduction reaction (NRR).