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

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.