Phosphorus-doped activated carbon as a platinum-based catalyst support for electrocatalytic hydrogen evolution reaction

Carbon is an excellent support that may influence the electronic structure of metal particles. However, carbon lacks functional groups on its surface, making it unsuitable for carrying catalysts, resulting in metal agglomeration. This can be solved by heteroatom doping to effectively optimize ligand structure and electronic characteristics of carbon materials, as well as enhance the intrinsic activity and steadiness of Pt/C catalysts. Herein, phosphorus-doped activated carbon (P-AC) was prepared as support for Pt catalysts to enhance the hydrogen evolution reaction (HER) under alkaline conditions. The main doped form of P-AC by potassium dihydrogen phosphate was identified as C3-PO, considered the most stable phosphorus-oxygen functional group in the carbon lattice with a key role in the HER process. The existence of C3-PO enhanced the interaction between P-AC and Pt nanoparticles, thereby tuning the electronic state of Pt and further optimising the adsorption of H* on Pt. Consequently, the resulting Pt/P-AC catalysts exhibited excellent HER activity (Tafel slope: 33.0 mV·dec−1, overpotential: 36.1 mV), with 4.6-fold incremented mass activity (1.220 A·mgpt−1) at a voltage of 70 mV than commercial catalysts containing 40 wt% Pt/C (0.266 A·mgpt−1). Moreover, a remarkable electrochemically active surface area (ECSA) of 66.95 m2·gPt−1 was observed in the Pt/P-AC catalysts. The Pt/P-AC catalysts also displayed high stability with better activity loss than commercial 40% Pt/C after 10,000 cycles. In sum, the proposed method looks promising for future syntheses of novel HER catalysts with high HER performance under alkaline conditions.