Reduced graphene oxide nanosheets supported platinum nanoparticles with enhanced mass activity for efficient hydrogen evolution

Abstract

One strategy is synthesizing a low-loading platinum-based electrocatalyst and enhancing platinum utilization efficiency. In this study, platinum nanoparticles (Pt NPs) were embedded onto the reduced graphene oxide (rGO) nanosheet surface using solvothermal and chemical reduction processes. The experimental results illustrated that the developed Pt NPs/rGO NSs, which exhibit superior HER activity and excellent stability, require only a low Pt loading of 9.6 % wt. The fabricated Pt NPs@rGO demonstrated an overpotential of 27 mV, reaching a current density of 10 mA cm⁻² with a lower Tafel slope of 34 mV dec⁻¹ and high turnover frequency (0.25 s⁻¹) in 0.5 M H₂SO₄. The HER performance of the Pt NPs@rGO electrocatalyst surpassed that of Pt without rGO (80 mV) and Pt/C (46 mV) electrodes. This enhancement may be due to the formation of PtO bonding on the rGO surface, leading to increased H atom adsorption. Furthermore, the strong electronic coupling between the Pt NPs and the rGO support is more favorable than that between Pt NPs and the carbon support (Pt/C, 20 % wt.). Notably, the mass activity of Pt NPs@rGO (143 mA mg⁻¹) is 8-times greater than that of Pt/C (20 % wt.) (18 mA mg⁻¹) at an overpotential of 27 mV, demonstrating that low-loading Pt NPs onto the rGO surface is more efficient than that of the benchmark Pt/C (20 % wt.). Impedance spectroscopy confirmed a strong electronic coupling between Pt NPs and rGO NSs, leading to high HER performance and fast electron mobility and charge transfer kinetics. The Pt NPs@rGO also exhibited excellent long-term stability over 24 h, indicating robust electronic interaction between Pt and rGO. The superior HER activity of the Pt NPs@rGO electrocatalyst is ascribed to the suitability of rGO as a support.