Pore-space-partitioned and hetero-atom-enriched dual-redox scalable metal–organic framework synergistically boosts overall water splitting

Abstract

The development of bifunctional and durable electrocatalysts capable of driving both the oxygen and hydrogen evolution reactions (OER and HER) in a single electrolyte with high efficiency is critical to advance cost-effective total water splitting (TWS) and the deployment of sustainable hydrogen technologies. Herein, we report a chemically robust metal–organic framework (MOF), constructed from a dithiazole-based linker (DPTz), an ethereal dicarboxylate ligand, and an in situ-generated [Co₂(COO)₄N₄] secondary building unit (SBU), which exhibits a 3D bipillar-layer architecture and pore-partition-governed microporous channels. An effective synergy between the redox-active SBU and fused thiazole functionality, together with ample heteroatom-enriched one-dimensional channels, promotes rapid charge transport and highly accessible active sites. As a result, the MOF delivers outstanding OER and HER activities in 1 M KOH, requiring markedly low overpotentials of 242 mV and 107 mV at 10 mA cm⁻², respectively, along with low Tafel slopes and fast interfacial charge transfer that surpasses the majority of MOF-based and some commercial catalysts. The material displays high faradaic efficiencies (OER: 93.67%; HER: 94.27%) with admirable long-term durability (>50 h), and superior intrinsic activity compared to many reported contemporary systems. Notably, this dual-redox MOF-devised symmetric electrolyser requires only 1.58 V to attain 10 mA cm⁻² for overall water splitting, outperforming commercial RuO₂‖Pt/C cells and exhibiting a steady performance over prolonged operation. The synergistic role of metal–ligand redox interplay is established from inferior performances of two structurally analogous mono-redox MOFs that preclude DPTz linker, and further supported by density functional theory (DFT) calculations. These findings offer valuable insights into the coherent design and hierarchical pore functionality engineering of framework materials to boost their electrochemical efficacy and provide a promising strategy for designing scalable bifunctional electrocatalysts for high-performance single-phase water splitting.