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 oxygen and hydrogen evolution reactions (OER and HER) in a single electrolyte with high efficiency is critical to advancing cost-effective total water splitting (TWS) and deployment of sustainable hydrogen technologies. Herein, we report a chemo-robust metal-organic framework (MOF), constructed from dithiazole-based linker (DPTz), ethereal dicarboxylate ligand, and in-situ generated [Co₂(COO)₄N₄] secondary building unit (SBU), which exhibits 3D bipillar-layer architecture and pore-partition governed microporous channels. Effective synergy between the redox-active SBU and fused thiazole functionality, together with ample heteroatom-enriched one-diemsional 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 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, as validated by specific, mass-normalized, and TOF analyses. Notably, this dual-rodox MOF-devised symmetric electrolyser requires only 1.58 V to attain 10 mA cm^‒2 for overall water splitting that outperforms commercial RuO2||Pt/C cells, and exhibits maintenance of steady performance over prolonged operation. The synergistic role of metal node-organic strut bimodal redox sites and heteroatoms is established from inferior performances of two structurally analogous mono-redox MOFs, precluding DPTz linker as well as density functional theory calculations. The findings offer valuable insights into coherent design and hierarchical pore functionality engineering in framework materials to boost the electrochemical efficacy, and provide a promising strategy in designing scalable bifunctional electrocatalysts for high-performance single-phase water‐splitting.