In Situ Reconstruction of Self-Supported Cu–Co–B Electrocatalyst to Achieve Highly Efficient Hydrogen Evolution

The development of economical and efficient catalysts for the hydrogen evolution reaction (HER) is critical for achieving low-energy water splitting. This study demonstrates that self-supported Cu–Co–B/NF, synthesized via the one-pot NaBH4 reduction, is converted into the active species Cu–Co(OH)2 during the HER process. This in situ conversion was verified through XRD, HRTEM, XPS, and other characterization techniques. This noble-metal free catalyst exhibits exceptional HER performance. It requires overpotentials of only 32 mV and 148 mV to achieve the current densities of 10 mA cm–2 and 500 mA cm–2, respectively, and maintains stability for over 200 h at a current density of 200 mA cm–2. The density functional theory (DFT) calculations reveal that the Co(OH)2 holds the active site, while the introduction of copper optimizes both the hydrogen adsorption free energy (ΔGH*) and the d-band center, thereby enhancing the catalytic activity. More than water electrolysis, an Al–H2O battery employing Cu–Co–B/NF as the positive electrode achieves a high open-circuit voltage (1.29 V) and a maximum power density of 11.17 mW cm–2.