Nanomaterials-Decorated Biomass-Derived Carbon for Overall Water Splitting: Interfacial Engineering, Mechanistic Insights, and Device Translation.

Green hydrogen produced by electrochemical water splitting is central to decarbonizing energy conversion, yet large-scale deployment is constrained by the cost and durability of noble-metal catalysts and sluggish oxygen evolution kinetics. Biomass-derived carbon (BDC) has emerged as a sustainable electrocatalyst scaffold owing to its abundance, low-cost, chemical robustness, and tunable hierarchical porosity, although pristine BDC often exhibits limited conductivity and insufficient active sites. This review consolidates advances in nanomaterials-decorated BDC electrocatalysts for overall water splitting, including metals and alloys, oxides, and hydroxides, sulfides and selenides, carbides and phosphides, heteroatom-doped carbons, and single-atom catalysts. We correlate synthesis strategies with morphological, electronic, and defect engineering and analyze performance metrics including overpotential, Tafel slope, electrochemical surface area, turnover frequency, Faradaic efficiency, and durability. Emphasis is placed on how metal-carbon and single-atom-carbon interfaces regulate adsorption energies of H*, OH*, O*, and OOH*. Degradation pathways, including nanoparticle aggregation, metal leaching, carbon corrosion, and surface reconstruction, are evaluated with practical mitigation strategies. Device-level demonstrations and density functional theory are summarized to guide rational catalyst design. By integrating materials chemistry, mechanistic insights, and application perspectives, this review establishes design principles, benchmarking recommendations, and directions for scalable, durable, cost-effective BDC-based bifunctional electrocatalysts.