Strategic drive toward bi-linker MOFs: an efficient electrocatalyst for hydrogen and oxygen evolution reactions

Abstract

This study demonstrates a transformative advance in electrocatalyst design through the strategic integration of bifunctional linkers in copper-based MOFs for overall water splitting. By engineering a dual-linker architecture incorporating 1,2,4,5-benzenetetracarboxylic acid (H₄BTEC) and 2-methylimidazole (2-MIM), we have developed a Cu-MOF electrode that simultaneously overcomes the fundamental limitations of conductivity, kinetics, and stability that plague conventional single-linker systems. Comprehensive electrochemical characterization revealed exceptional bifunctional performance: an overpotential of just 234.7 mV for HER and 169.8 mV for OER, substantially outperforming single-component analogues (H₄BTEC-MOF: 288.5 mV HER, 291.0 mV OER; 2-MIM-MOF: 298.1 mV HER, 386.5 mV OER). Kinetic superiority was evidenced by record-low Tafel slopes (18.1 mV per dec HER; 71.6 mV per dec OER) and a four-fold reduction in charge-transfer resistance (1.1 Ω vs. 2.6–3.2 Ω). The hierarchical porous structure, confirmed by morphological and structural analyses, facilitates efficient mass transport and exposes abundant active sites. This molecular engineering strategy effectively resolves the classic trade-off between conductivity, kinetics, and stability in electrocatalysis, establishing a new paradigm for designing non-precious metal electrocatalysts for sustainable hydrogen production.