Constructing partially amorphous borate doped iron-nickel nitrate hydroxide nanoarrays by rapid microwave activation for oxygen evolution

Abstract

Metal nitrate hydroxides (MNHs) show great potential in the field of electrocatalytic water splitting, especially for oxygen evolution reaction (OER). The conversion of crystalline transition metal-based catalysts into partially amorphous counterparts is considered to be a promising but challenging strategy for improving OER performance of MNHS. Here, a simple and rapid microwave method is reported to synthesize partially amorphous borate doped iron-nickel nitrate hydroxide nanoarray uniformly grown on conductive iron foam (m-B-FeNiNH/IF) for OER. The microwave activation can promote the formation of the partial amorphous structure, leading to optimize geometric, electronic structure, and produce more high intrinsic activity. Moreover, with the addition of borate, synergistically promoted FeOOH (Fe4(NO)3(OH)11 → FeOOH) as active species may significantly improve OER performance with a low overpotentials of only 246 mV at 100 mA cm−2 and a 26.5 mV dec−1 Tafel slope, outperforming most of the non-noble metal based catalysts reported. The partially amorphous and self-supported m-B-FeNiNH/IF maintain catalytic durability and structural integrity for 100 h at 100 mA cm−2 large-current-density. This work may provide insights into improving electrocatalytic performance by introducing partially amorphous structures.