Biochar-derived carbon-encapsulated bimetallic nanoparticles for selective aqueous formic acid dehydrogenation via electronic modulation

Efficient and resource- abundant heterogeneous catalysts for formic acid (FA) dehydrogenation are essential for realizing a sustainable hydrogen energy cycle. However, earth-abundant non-noble metal catalysts are severely limited by intrinsically sluggish C–H activation, acid-induced metal leaching and rapid CO poisoning from the competing dehydration pathway. To address these challenges, we propose a synergistic strategy integrating spatial confinement with alloy electronic modulation to synthesize a series of bimetallic nanoparticles encapsulated within biocarbon shells (NiM@BC). Among the synthesized catalysts, NiCo@BC exhibits outstanding catalytic performance, achieving a gas generation rate of 634 mL·g −1 ·h −1 at 95 °C (nearly twice that of monometallic Ni@BC) and drastically reducing the CO concentration from 8350 to 1240 ppm, along with excellent durability over multiple cycles. Structural characterizations confirm that NiCo alloy nanoparticles are uniformly encapsulated within a robust graphitic carbon shell, which prevents metal leaching and suppresses aggregation. Kinetic analysis and density functional theory calculations reveal that Co incorporation moderately shifts the Ni d-band center to an optimal position. The electronic modulation lowers the energy barrier of the rate-determining C–H bond cleavage, while simultaneously raising the dehydration barrier significantly, thereby widening the energetic gap between dehydrogenation and CO-forming pathways. This work provides a systematic theoretical foundation for the high-value utilization of biomass and the development of CO-resistant, durable, and precious-metal-free catalytic systems for FA dehydrogenation.