Regulating the Band Structure of Ni Active Sites in Few‐Layered Nife‐LDH by In Situ Adsorbed Borate for Ampere‐Level Oxygen Evolution

Abstract Realizing rapid transformation of hydroxide to high‐active oxyhydroxide species in layered double hydroxide (LDH) catalyst plays a significant role in enhancing its activity toward oxygen evolution reaction (OER) for hydrogen production from water. Here, a scalable strategy is developed to synthesize defect‐rich few‐layered NiFe‐LDH nanosheets (f‐NiFe‐LDH‐B) with in situ borate modified for boosted and stable OER due to that the borate can narrow the bandgap for Ni sites to realize a more conductive electronic structure. Besides, the adsorbed borate can tune the d band center of Ni sites to promote of hydroxide transformation and facilitate the adsorption of the OER intermediates. The f‐NiFe‐LDH‐B catalyst, therefore, requires only 209 and 249 mV overpotential to deliver 10 and 100 mA cm −2 OER, respectively, with a Tafel slope of 43.5 mV dec −1 . Moreover, only 1.8 V cell voltage is required to reach Ampere‐level overall water splitting for 500 h at room temperature.