Enhanced Reaction of Renewable Hydrogen Energy Production Using Platinum-based Nanoclusters

Abstract

Objectives It would be essential for solving the global warming problem to use renewable energy as well as increase the efficiency of energy production. One of the renewable and efficient energy sources is hydrogen energy, and the electrochemical hydrogen evolution reaction (HER) is the most important reaction in the hydrogen energy production. For HER, inexpensive catalyst development is indispensible because the precious metal Pt is being used as the most efficient catalyst for HER. Methods Density functional theory (DFT) calculations were performed using the Vienna ab initio simulation package (VASP) to calculate atomic and electronic structures and total energies using the projector-augmented wave (PAW) method. Results and Discussion The HER efficiencies of Pt(111), Pt nanoclusters, and Pt-based core-shell nanoclusters were examined based on the hydrogen adsorption energies (Eads) by using the density functional theory (DFT) calculations. The DFT results demonstrate that Pt nanoclusters (0.5 ~ 2.1 nm in diameter) showed stronger hydrogen adsorption (Eads = -0.65 ~ -1.25 eV) than that of Pt(111) (Eads = -0.61 eV), implying a lower HER efficiency of Pt nanoclusters than Pt(111). On the other hand, a Rucore-Ptshell nanocluster (Eads = -0.48 eV) showed weaker hydrogen adsorption than Pt(111), indicating an increase in the HER efficiency. The weaker hydrogen adsorption on Rucore-Ptshell was attributed to the d;-band shift of Pt atoms further away from the Fermi level in negative direction due to the core Ru atoms. Conclusion By evaluating the HER efficiency using a descriptor of the hydrogen atom adsorption strength, a Ru-Pt core-shell (Rucore-Ptshell) nanocluster was expected to exhibit the highest HER efficiency among Pt(111), Pt55 nanocluster, and Mcore-Ptshell (M = Ni, Co, Mn, Cu, Ru, Ir and Au) nanoclusters. Key words: Hydrogen Evolution Reaction (HER), Platinum (Pt) Catalysts, Nanocluster, Core-shell, Density Functional Theory (DFT), d-Band Center Theory