Engineering Carbon Cloth-Catalyst Interfaces for Pt-Free Hydrogen Evolution Across the Full pH Spectrum.

The development of Pt-free electrocatalysts is critical for reducing the cost of hydrogen production through the hydrogen evolution reaction (HER). Although extensive efforts have focused on improving the intrinsic activity of earth-abundant catalysts, the role of the catalyst-support interface remains comparatively underexplored. Carbon cloth (CC) has emerged as an attractive electrode platform owing to its electrical conductivity, hierarchical porosity, mechanical flexibility, chemical stability, and ability to facilitate efficient charge and mass transport. Although CC is generally not the primary HER active phase, it can strongly influence electrode-level performance by regulating interfacial electron transfer, catalyst anchoring, active-site accessibility, wettability, hydrogen bubble release, and long-term durability. This review critically analyzes the interfacial synergy between CC and Pt-free transition-metal-based catalysts, including Co-, Ni-, Fe-, Cu-, Mo-, and W-based systems, with and without heteroatom or anion modification involving N, P, and S species. The HER activity and stability of these systems are evaluated under acidic, alkaline, neutral, and pH-universal conditions. A particular emphasis is placed on how catalyst-support interactions, synthesis strategies, surface chemistry, structural features, and mass-transport behavior collectively determine electrochemical performance. Finally, current challenges and future opportunities are discussed, including mechanistic understanding, operando characterization, high-current-density operation, long-term durability, scalable fabrication, and practical electrolyzer integration.