Factors Influencing Catalytic Activity of Size-Specific Triphenylphosphine-Ligated Gold Nanoclusters in the Electrocatalytic Hydrogen Evolution Reaction

Hydrogen production via electrocatalytic water splitting has attracted growing attention as an alternative renewable and clean energy source. Size-specific gold nanoclusters and complexes (AuNCs) can serve as models for investigating the catalytic behavior toward the hydrogen evolution reaction (HER) at the atomic level. This work is focused on exploring the factors influencing the catalytic activity of phosphine-ligated AuNCs as electrocatalysts for improving HER performance using Au-101(PPh3)(21)Cl-5, Au-9(PPh3)(8)(NO3)(3), and Au-1(PPh3)Cl supported on reduced graphene oxide (rGO). Production of AuNC-rGO nanocomposites without agglomeration of the AuNCs was confirmed by transmission electron microscopy, X-ray photoelectron spectroscopy, and visible light absorbance. The weight loading of gold in the nanocomposite material was confirmed to be approximate to 5 wt % by thermogravimetric analysis and inductively coupled plasma mass spectrometry. Electrocatalytic performance of the AuNCs was determined through linear sweep voltammograms in 0.5 M sulfuric acid. Greater performance was observed for Au101NC-rGO, while Au9NC-rGO and Au1NC-rGO showed similar performance. The stability of each AuNC was determined through extended chronoamperometry experiments, and negligible reduction in performance was observed for Au101NC-rGO and Au9NC-rGO, while Au1NC-rGO was less stable. The variation in performance was attributed to a range of factors including catalyst size, electronic structure, and ligand density. This work provides guidelines to design highly efficient electrocatalysts using ligated metal clusters.

Automated summary

This study focuses on investigating the factors influencing the catalytic activity of phosphine-ligated AuNCs for improving hydrogen evolution reaction (HER) performance. Different AuNCs supported on reduced graphene oxide (rGO) showed varied electrocatalytic performance, with Au101NC-rGO demonstrating the highest performance. Factors such as catalyst size, electronic structure, and ligand density were found to contribute to the variation in performance, providing guidelines for designing highly efficient electrocatalysts using ligated metal clusters.