Boron-Insertion-Induced Lattice Engineering of Rh Nanocrystals Toward Enhanced Electrocatalytic Conversion of Nitric Oxide to Ammonia

Electrocatalytic nitric oxide (NO) reduction reaction (NORR) is a promising and sustainable process that can simultaneously realize green ammonia (NH 3 ) synthesis and hazardous NO removal. However, current NORR performances are far from practical needs due to the lack of efficient electrocatalysts. Engineering the lattice of metal-based nanomaterials via phase control has emerged as an effective strategy to modulate their intrinsic electrocatalytic properties. Herein, we realize boron (B)-insertion-induced phase regulation of rhodium (Rh) nanocrystals to obtain amorphous Rh 4 B nanoparticles (NPs) and hexagonal close-packed ( hcp ) RhB NPs through a facile wet-chemical method. A high Faradaic efficiency (92.1 ± 1.2%) and NH 3 yield rate (629.5 ± 11.0 µmol h −1 cm −2 ) are achieved over hcp RhB NPs, far superior to those of most reported NORR nanocatalysts. In situ spectro-electrochemical analysis and density functional theory simulations reveal that the excellent electrocatalytic performances of hcp RhB NPs are attributed to the upshift of d-band center, enhanced NO adsorption/activation profile, and greatly reduced energy barrier of the rate-determining step. A demonstrative Zn–NO battery is assembled using hcp RhB NPs as the cathode and delivers a peak power density of 4.33 mW cm −2 , realizing simultaneous NO removal, NH 3 synthesis, and electricity output.