This paper describes the effects of doped metals on hydrogen evolution reaction (HER) electrocatalyzed by atomically controlled MAu 24 and M 2 Au 36 nanoclusters, where M = Pt and Pd. HER performances, such as onset potential (E onset ), catalytic current density, and turnover frequency (TOF), are comparatively examined with respect to the doped metals. Doping Pt or Pd into gold nanoclusters not only changes the electrochemical redox potentials of nanoclusters but also considerably improves the HER activities. E onset is found to be controlled by the nanocluster's reduction potential matching the reduction potential of H + . The higher catalytic current and TOF are observed with the doped nanoclusters in the order of PtAu 24 > PdAu 24 > Au 25 . The same trend is observed with the Au 38 group (Pt 2 Au 36 > Pd 2 Au 36 > Au 38 ). Density functional theory calculations have revealed that the hydrogen adsorption free energy (G H ) is significantly lowered by metal-doping in the order of Au 25 > PdAu 24 > PtAu 24 and Au 38 > Pd 2 Au 36 > Pt 2 Au 36 , indicating that hydrogen adsorption on the active site of nanocluster is thermodynamically favored by Pd-doping and further by Pt-doping. The doped metals, albeit buried in the core of the nanoclusters, have profound impact on their HER activities by altering their reduction potentials and hydrogen adsorption free energies.
Bibliographical noteFunding Information:
This work was supported by the Korea CCS R&D Center (KCRC) Grant (NRF-2014M1A8A1074219) and NRF Grants NRF-2017R1A2B3006651 and NRF-2009-0093823. Computation by DFT (G.H. and D.-e.J.) was sponsored by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division.
© Copyright 2018 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)