Pore Expansion of N-Doped Carbon as Support of Pd Catalyst for Accelerated Formic Acid Dehydrogenation

Formic acid offers a fascinating medium for hydrogen storage and transport, and Pd@carbon catalysts are the most common catalysts for catalyzing the release of hydrogen from formic acid (dehydrogenation). Biomass-derived carbon is advantageous over other supports in view of cost, sustainability, and easy modification. Nitrogen (N) doping of carbon can improve the activity of a carbon-supported Pd catalyst, but the concurrently deteriorated porosity of carbon inhibits it from reaching the full potential. Herein, the pores of N-doped wood-derived carbon were expanded by a novel alkali/air coactivation method so as to enhance further the activity of Pd@carbon catalyst for formic acid dehydrogenation. After investigation of the influence of N doping and coactivation conditions, the N-doped porous carbon (NPC) with developed porosity (SABET = 956 m2<middle dot>g-1, and SAmeso = 295 m2<middle dot>g-1) was produced at optimized conditions. The Pd@NPC catalyst with well-distributed ultrafine Pd nanoparticles (0.4-1.4 nm) was synthesized by taking advantage of both N doping and expanded pores (especially mesopores) of NPC. Subsequently, a turnover frequency of 446 h-1 was obtained using this Pd@NPC catalyst for additive-free formic acid dehydrogenation at 303 K. Thus, formic acid dehydrogenation was accelerated by expanding the pores of N-doped biomass-derived carbon that acted as a support of Pd catalysts.