Abstract
Direct formic acid fuel cells (DFAFCs) offer a liquid-fuel alternative to hydrogen-fed proton-exchange membrane fuel cells, but inconsistent designs and operating conditions hinder performance comparison. This review benchmarks experimentally tested single-cell DFAFCs across Pt-, Pd-, Pt–Pd-, and non-noble-metal catalyst systems by peak power density, catalyst loading, durability, and operating conditions. Reported peak power densities range from 20 to 550 mW cm⁻². Pd–Ni₂P/C achieved 550 mW cm⁻², while PtBiPbNiCo reached 321.2 mW cm⁻². FeTSPc-promoted Pt increased peak power density from 76.3 to 126.6 mW cm⁻² and suppressed CO-forming pathways; a Co–NCNT cathode achieved 160.7 mW cm⁻², exceeding the corresponding Pt/C reference. However, inconsistent durability tests and cell configurations prevent reliable cross-study ranking and commercial-readiness assessment. A baseline protocol is proposed, specifying operation at 60 °C with 3 M formic acid, controlled oxidant supply, defined membrane-electrode assembly geometry, liquid-compatible anode diffusion layers, and at least 100 h of durability testing. The protocol is designed to generate interoperable, machine-readable datasets, which are a prerequisite for digital twins, predictive degradation assessment and real-time energy management of DFAFC-based hybrid transport power systems. Standardized full-cell testing can distinguish catalyst improvements from configuration effects and support reproducible DFAFC development.