Template-Guided Synthesis of Cubic Cu–Rh Alloy Nanoframes for Electrochemical Nitrite-to-Ammonia Conversion via Tandem Catalysis

Alloyed nanoframes (NFs), featuring high metal atomic utilization efficiency and large specific surface areas, have shown great promise for electrocatalysis. However, the rational design and precise synthesis of structurally stable NF catalysts remain considerable challenges. Herein, we report a template-guided strategy for constructing alloyed Cu x Rh y NFs via the selective etching of Cu atoms from the low-energy facets of Cu nanocubes (NCs) using a Cl – /O 2 pair, followed by the galvanic replacement of Cu atoms with Rh at the frame edges and vertices. Notably, the Cu 24 Rh 76 NFs deliver outstanding electrocatalytic performance toward the nitrite reduction reaction (NO 2 RR), achieving an NH 3 Faradaic efficiency (FE) of 99.6% at 0 V (vs the reversible hydrogen electrode (RHE)) and an NH 3 yield rate of 676.7 mmol h –1 g –1 at −0.4 V. Such remarkable electrocatalytic performance for NH 3 production arises from not only the unique three-dimensional (3D) ultrathin frame architecture but also a tandem catalytic mechanism. During the NO 2 RR process, Cu sites adsorb and activate NO 2 – to produce the *NO intermediate, while Rh sites generate *H species that migrate to the *NO intermediates adsorbed on Cu sites, effectively promoting the subsequent hydrogenation steps toward NH 3 generation.