Engineering 1 T-rich MoS₂-tuned FeNiCo-based metal-organic framework heterostructure for enhanced oxygen evolution...

The sluggish kinetics of the oxygen evolution reaction (OER) remains a major bottleneck for efficient water splitting. Despite being promising alkaline OER catalysts, most two-dimensional (2D) metal-organic frameworks (MOFs) undego kinetically uncontrolled reconstruction into metal (oxy)hydroxides (MOOH), leading to insufficient intrinsic activity and poor stability. More importantly, the electronic modulation of the pre-catalysts is crucial to forming highly active and stable MOOH for steering the reconstruction kinetics. Herein, a heterojunction pre-catalyst is fabricated by in situ growth of FeNiCo-BDC (FNC) on 1 T-phase-dominated MoS₂ nanosheets supported by carbon cloth (CC) (FNC@MoS₂/CC). Comprehensive experimental and theoretical analyses reveal that the pre-catalyst possesses an advantageous electronic structure, featuring interfacial electron-rich metal sites induced by bidirectional electron transfe. This leads to a downshifted d-band center position, accelerated charge transfer, and optimized adsorption/desorption of OER intermediates. Crucially, in situ investigations demonsreate that this modulated electron regulation of FNC@MoS₂/CC controls the kinetics of electrochemical reconstruction, thus facilitating the transformation toward a highly active and ctive and stable catalytic MOOH@MoS₂. Consequensely, FNC@MoS₂/CC achieves an ultralow overpotential of 188 mV at 10 mA cm^-2 and outstanding stability over 100 h for OER. Furthermore, it enables efficient overall water splitting with a low cell potential of 1.539 V at 10 mA cm^-2. Notably, in an 25 °C anion-exchange-membrane electrolyzer, a FNC@MoS₂/CC (+,-) couple displays 500 mA cm^-2 at only 1.87 V and operates stably over 200 h. This work highlights that engineering pre-catalysts to steer dynamic surface reconstruction is an pivotal strategy for advanced OER electrocatalysis.