Biomass-Derived Carbon Supported Bimetal Hydroxide for Hydrogen Generation

Abstract

Searching for an efficient electrocatalyst remains a major challenge for hydrogen production in the commercial application of water splitting. Herein, we report newly designed material of Res(Ce)-TMs(Ni) carbonate hydroxide embedded with an activated cashew shell carbon (CSK) as scaffold to explore the origin of Ce-triggered kinetics of Ni sites in CNCH-CSK towards HER and OER. The synergistic effect of Ce-coupling with NCH-CSK enhances the active surface area, exposing more active sites, improving porosity and promoting intimate contact between CNCH-CSK and current collector, thereby regulating the electronic redistribution of Ni sites for enhanced activity. CNCH-CSK exhibits exceptional bifunctional activity with high durability (OER: 121 ± 2 mV, 32.3 ± 5 mV dec-1, 3.14 Ω; HER: 98 ± 2 mV, 33.6 ± 5 mV dec-1; 2.36 Ω). The reaction kinetics of CNCH-CSK catalysis were monitored via in situ EIS, revealing minimal activation energy after Ce coupling, as confirmed by the Arrhenius plot. The higher rate constant extracted from the trumpet plot for CNCH-CSK at various pH values indicates vigorous gas bubble formation. Enhanced *OH adsorption on CNCH-CSK was further verified by Laviron analysis. The alkaline-/solar-driven electrolyzer of CNCH-CSK(+,-) required 1.46V to achieve a current density of 10 mA cm-2 indicating promising prospects for practical applications. Furthermore, when integrated into an anion exchange membrane water electrolyzer (AEMWE), CNCH-CSK delivers a current density of 100 mA cm⁻² at 1.57V, demonstrating its strong potential as a bifunctional catalyst. The exceptional Ce4f valence electronic structure directs Ni active sites toward enhanced HER and OER performance via Ce4f–Ni3d orbital coupling. The Ce4f states facilitate *H intermediate adsorption during HER, while the Ce4f band provides additional spin coupling with reaction intermediates during OER. This work highlights rare-earth (RE)-induced differentiated regulatory effects in transition metal (TM)-based catalysts for green hydrogen generation.