Gold–Rhodium Nanoflowers for the Plasmon-Enhanced Hydrogen Evolution Reaction under Visible Light

Leonardo De O Cutolo,Tiago Vinicius Alves,Pedro H C Camargo,Susana Inés Cordoba De Torresi,Sarah J Haigh,Thomas J A Slater,André H B Dourado,Maria Paula De Souza Rodrigues,Luanna S Parreira

doi:10.1021/acscatal.1c02938

Abstract

State of the art electrocatalysts for the hydrogen evolution reaction (HER) are based on metal nanoparticles (NPs). It has been shown that the localized surface plasmon resonance (LSPR) excitation in plasmonic NPs can be harvested to accelerate a variety of molecular transformations. This enables the utilization of visible light as an energy input to enhance HER performances. However, most metals that are active toward the HER do not support LSPR excitation in the visible or near-IR ranges. We describe herein the synthesis of gold–rhodium core–shell nanoflowers (Au@Rh NFs) that are composed of a core made up of spherical Au NPs and shells containing Rh branches. The Au@Rh NFs were employed as a model system to probe how the LSPR excitation from Au NPs can lead to an enhancement in the HER performance for Rh. Our data demonstrate that the LSPR excitation at 533 nm (and 405 nm) leads to an improvement in the HER performance of Rh, which depends on the morphological features of the Au@Rh NFs, offering opportunities for optimization of the catalytic performance. Control experiments indicate that this improvement originates from the stronger interaction of Au@Rh NFs with H2O molecules at the surface, leading to an icelike configuration, which facilitated the HER under LSPR excitation.

Highlights

Hydrogen (H2) represents one of the most promising energy carriers to address challenges related to renewable energy.[1]
We report on the controlled synthesis of gold−rhodium core−shell nanoflowers (Au@Rh NFs) that are comprised of a spherical Au nanoparticle (NP) core and a shell containing Rh branches or small NPs
Our results demonstrated that the localized surface plasmon resonance (LSPR) excitation at 533 nm led to an improvement in the hydrogen evolution reaction (HER) performances

Summary

■ INTRODUCTION

We wanted to investigate how the bimetallic composition of the NFs (without light excitation) influence their activities toward the HER In this case, we were interested in probing if the bimetallic composition could enable different adsorption interactions with water that could lead to improvements in the HER relative to the monometallic NPs. We performed in situ Fourier transform infrared spectroelectrochemistry experiments to gain further insights into the intermediates involved in the hydrogen evolution reaction. The bimetallic composition contributes to increasing the strength of adsorbed H2O at the surface of the NFs, which preferentially leads to an icelike or interfacial water conformation, as suggested by the in situ FTIR This enables a significant increase in HER performance relative to the monometallic systems, showing that this conformation is favoring the electron transfer simultaneously with the water self-ionization,[72,74] even in the absence of light excitation. These sites are expected to contribute to a large optical absorption and charge transfer to adsorbed water species

■ CONCLUSION

■ REFERENCES

Findings

■ ACKNOWLEDGMENTS