Laser-Regulated CoFeRu-LDH Nanostructures: Nitrite-to-Ammonia Production in Zn-Nitrite Battery and Oxygen Evolution in Water Electrolysis.

Herein, the design and synthesis of Ru-doped CoFe-layered double hydroxide (CoFeRu─LDH) nanostructures is presented via an innovative yet straightforward pulsed laser method. The CoFeRu─LDH catalyst demonstrates outstanding electrocatalytic performance, achieving a high NH Faradaic efficiency (FE) of 89.65% at -0.7 V versus reversible hydrogen electrode for nitrite reduction reaction (NO RR) and a low overpotential of 297 mV at 10 mA cm for oxygen evolution reaction (OER). Comprehensive in situ and ex situ analyses reveal the electrochemically energetic species formed on the CoFeRu─LDH surface during the NO RR and OER. Theoretical studies confirm that Ru doping plays an imperative role in tuning the electronic structure of CoFeRu─LDH, lowering its reaction barriers, and thereby remarkably enhancing its NO RR and OER performance. Specifically, a galvanic Zn-nitrite battery using CoFeRu─LDH as the cathode efficiently converts NO to NH with an FE of 96.8% while concurrently generating electricity with a power density of 4.14 mV cm. Furthermore, pairing CoFeRu─LDH as the anode with Pt/C as the cathode in water electrolysis enables H production at a low cell voltage of 1.57 V at 10 mA cm. This study presents a new pathway to designing versatile, high-performance electrocatalysts for sustainable energy conversion and the production of carbon-free NH and H fuels.