Highly selective electrocatalytic hydrogenation of benzoic acid over Pt/C catalyst supported on carbon fiber

Cyclohexanecarboxylic acid (CCA), an important chemical and pharmaceutical intermediate, is commonly produced from thermal catalytic hydrogenation of benzoic acid (BA) under high temperature and pressure. Herein, electrocatalytic hydrogenation (ECH) for highly selective conversion of BA into CCA using carbon fibers with different graphitization degree (carbon fiber paper (CFP), carbon fiber cloth (CFC)) supported commercial platinum carbon (Pt/C) electrode was reported for the first time without using external H2. Our experimental results show that, at room temperature and 1 atm, the BA conversion and the CCA selectivity are both as high as 100% in 0.05 M H2SO4 over carbon fiber paper (CFP)-supported Pt/C (Pt/C/CFP). Meanwhile, Pt/C/CFP electrode still maintains outstanding stability after 10 reaction cycles. In situ Raman results and theoretical calculations reveal that the adsorption strength of BA over Pt/C/carbon fibers electrode varies with the graphitization degree of carbon fibers along with the applied potential. The superior ECH performance of the Pt/C/CFP is mainly attributed to the high dispersity of Pt/C catalysts on CFP as well as unique electronic interaction, which improved the adsorption and activation of BA. Typically, CFP with few defects can induce the accumulation of electrons around the Pt regions and enhance the electron-deficient aromatic adsorption thus improving the ECH performance of Pt/C/CFP, which is the opposite for CFC with more defects.