Cost-Effective Platinum Single Atom Catalyst Synthesized through Chemical Diazonium Grafting on Carbon Cloth for Efficient Electrocatalytic Hydrogen Evolution

Platinum single atom catalyst (PtSAC) has been considered an ideal material for electrocatalytic hydrogen evolution, offering high atom economy, making every platinum atom participate in the reaction. However, the synthesis of PtSAC usually involves high temperature and sophisticated instrumentation, limiting its accessibility and scalability. Herein, we report a novel PtSAC synthetic approach by chemical diazonium grafting of 3-pyridyl ligands onto carbon cloth, generating a coordination layer. The grafted 3-pyridyl ligands on the carbon surface were used to capture platinum by submerging in Pt2+ solution, generating PtSAC on carbon cloth (PtSAC@CC). The robust coordination structure allows the PtSAC@CC to remain stable in 4 M H2SO4 at 80°C. With its ultra-low Pt loading, 0.182 and 0.380 μg/cm2, PtSAC@CCs present high current density (mA/cm2) for hydrogen evolution reaction, similar to commercially available low platinum content carbon cloth electrodes (Pt/C@CC). This highlights its significant metal utilization efficiency by achieving up to 53 times higher mass activity than Pt/C@CC at low overpotential. During hydrogen evolution, the chlorine co-ligands were substituted by hydroxy groups, leading to an enhanced performance as revealed by DFT calculations. In addition, the formed hydrogen bubbles departed from PtSAC@CC surface at a small size between 70 and 110 μm in diameter. This excellent bubble management successfully prevents the blockage of catalytic sites while maintaining stable hydrogen production. This cost-effective PtSAC synthesis method not only utilizes low-cost reagents to modify the carbon cloth with 3-pyridyl ligands but also minimizes the platinum loading to an extremely low level, which enhances its competitiveness for large-scale use.