Green construction of CoNiB₂ nanoflowers towards OER catalyst by interactive coupling the raw oxides via liquid soaking for a few seconds

Developing efficient and stable oxygen evolution reaction (OER) electrocatalysts based on non-precious metals is crucial for cost-effective hydrogen production. Herein, we report the rapid synthesis of crystalline cobalt–nickel boride (CoNiB₂) nanoflowers via a liquid-phase soaking technology (LST). Using liquid boron oxide as the reaction medium enables the synthesis of highly active CoNiB₂ catalysts in just 20 s. CoNiB₂ exhibits a lower energy barrier for the rate-determining step compared to CoB. As a result, the CoNiB₂ catalyst exhibits outstanding OER performance in alkaline media, requiring an overpotential of only 271 mV to achieve 10 mA cm⁻² and demonstrating a low Tafel slope of 67 mV dec⁻¹. Furthermore, no significant performance degradation was observed after 25 h of operation at 100 mA cm⁻².