NaBH4-electrooxidation mediated electrodeposition of catalytic Pt nanoparticles on a honeycomb-gold electrode for hydrogen evolution reaction

Abstract We report the NaBH4-electrooxidation mediated electrodeposition of platinum nanoparticles (PtNPs) on a pulse-plated gold (Aupla) and three-dimensional honeycomb-like porous nano-golds (3DHPNG) modified glassy carbon electrode (GCE), for electrocatalytic hydrogen evolution reaction (HER). The 3DHPNG of large surface area was deposited on Aupla/GCE at −4.76 V versus RHE for 200 s in 5 M aqueous H2SO4 containing 15 mM HAuCl4, by dynamic hydrogen bubble template. The uniform electrodeposition of PtNPs on 3DHPNG/Aupla/GCE at 1.24 V versus RHE was achieved in 25 mM aqueous NaClO4 containing 5.37 μM PtNPs dispersion that was obtained by mixing aqueous NaBH4, trisodium citrate and H2PtCl6. The electrodeposition mechanism is explained by the electrogeneration of H+ through the electrooxidation of residual NaBH4 and its oxidation intermediates, which can neutralize the negative surface-charges of some PtNPs and make the PtNPs coagulate on the electrode surface, and some new insights into the oxidation of so widely used NaBH4 on the anode and by H2PtCl6 and water are also provided. The optimized PtNPs/3DHPNG/Aupla/GCE exhibited good electrocatalytic performance for HER in 0.5 M aqueous H2SO4, giving an overpotential of 10.0 mV at −10 mA cm−2 and a Tafel slope of 25.2 mV dec−1, being better than those of many reported electrodes.