Thickness-dependent catalytic activity of hydrogen evolution based on single atomic catalyst of Pt above MXene

TL;DR

This study uses ab initio calculations to explore how the thickness of MXene layers influences the catalytic activity of single-atom platinum catalysts for hydrogen evolution, revealing optimal configurations for high efficiency.

Contribution

It demonstrates the significant impact of MXene layer thickness and surface termination on HER catalytic performance, highlighting the importance of substrate engineering.

Findings

Ti2CF2-PtSA and Ti2CH2O2-PtSA are the best HER catalysts with near thermoneutral Gibbs free energy.

The catalytic activity is strongly affected by MXene thickness, not just local surface environment.

These catalysts exhibit good thermodynamic stability according to molecular dynamics simulations.

Abstract

Hydrogen as the cleanest energy carrier is a promising alternative renewable resource to fossil fuels. There is an ever-increasing interest in exploring efficient and cost-effective approaches of hydrogen production. Recent experiments have shown that single platinum atom immobilized on the metal vacancies of MXenes allows a high-efficient hydrogen evolution reaction (HER). Here using ab initio calculations, we design a series of substitutional Pt-doped Tin+1CnTx (Tin+1CnTx-PtSA) with different thicknesses and terminations (n = 1, 2 and 3, Tx = O, F and OH), and investigate the quantum-confinement effect on the HER catalytic performance. Surprisingly, we reveal a strong thickness effect of the MXene layer on the HER performance. Amongst the various surface-terminated derivatives, Ti2CF2-PtSA and Ti2CH2O2-PtSA are found to be the best HER catalysts with the change of Gibbs free energy {\Delta}G*H ~ 0 eV, complying with the thermoneutral condition. The ab initio molecular dynamics simulations reveal that Ti2CF2-PtSA and Ti2CH2O2-PtSA possess a good thermodynamic stability. The present work shows that the HER catalytic activity of the MXene is not solely governed by the local environment of the surface such as Pt single atom. We point out the critical role of thickness control and surface decoration of substrate in achieving a high-performance HER catalytical activity.