Architecture Engineering and Phase Engineering of Rhodium Metallene Co-Boost Nitrite-to-Ammonia Electroconversion

Electrocatalytic nitrite reduction reaction (NO₂RR) offers an effective strategy for sustainable ammonia (NH₃) synthesis and N-pollutants wastewater degradation. Herein, we propose a dual-engineering strategy by combining architecture engineering and phase engineering on nanosheet-like rhodium metallene (Rh-NS) coupled with twisted nanoribbon-like rhodium metallene (Rh-NR) nanoarchitectonics (Rh-NS/Rh-NR) to boost NO₂ ^--to-NH₃ electroconversion. Rh-NS/Rh-NR, characterized by a high density of unsaturated coordination sites and a large specific surface area, greatly enhances the adsorption capacity of NO₂ ^- and crucial intermediates and lowers the energy barrier for the rate-determining step of *NOH formation from *NO. Consequently, Rh-NS/Rh-NR exhibits satisfactory Faradaic efficiency (FE) of 98.7% and a remarkable NH₃ yield rate of 44.3 mg mg_cat ^-1 h^-1 for NO₂RR at high reduction potential (0.00 V). Using Rh-NS/Rh-NR as cathode, the assembled zinc-nitrite battery delivers excellent discharge performance (24.2 mW cm^-2) and promising NH₃ synthesis capacity (5.96 mg mg_cat ^-1 h^-1). This work not only guides the architecture-engineering design of metallene but also demonstrates the practical potential of zinc-nitrite batteries in integrated energy-environmental applications.