Dual interface engineering of self-supported crystalline/amorphous NiO/Ni(OH)2 nanosheet arrays for efficient and stable H2O splitting

Self-supported nanoarrays have emerged as a promising alternative electrocatalyst for alkaline H 2 O splitting, owing to their accessible active sites and strongly coupled interfaces with current collectors for improved mass transfer and stability. Herein, self-supported crystalline/amorphous NiO/Ni(OH) 2 nanosheet arrays on nickel foam (NF) are fabricated via an in-situ dissolution-deposition hydrothermal growing of Ni(OH) 2 nanosheets without additional metal sources assisted by a common Lewis base, EDTA, followed by a rapid calcination at 300 ​°C in air. The as-prepared EDTA-NF-12 ​h exhibits high OER and HER performance under alkaline conditions, requiring 235 ​mV and 158 ​mV, respectively, to reach 10 ​mA ​cm −2 , and the decent performance can be maintained for 24 ​h without obvious degradation. The dual interfaces, i.e., the dense crystalline/amorphous interfaces within the NiO/Ni(OH) 2 nanosheet arrays, as well as the intimate interfaces between nanoarrays and NF, both serve as reaction active sites, facilitate electron transfer, and endow the catalyst with high activity and stability. Furthermore, by applying EDTA-Ni 2+ and other Lewis bases with varying basicities instead of EDTA, the interfaces with the NF substrate are found to promote the formation of crystalline/amorphous interfaces within the nanosheets. This study offers appealing opportunities for tailoring the electrocatalytic performance of self-supported electrodes via dual interface engineering.