Monolayer fullerene networks as photocatalysts for overall water splitting

TL;DR

This study uses advanced computational methods to analyze monolayer fullerene networks, revealing their suitable electronic and optical properties for efficient photocatalytic water splitting, highlighting their potential as novel photocatalysts.

Contribution

It demonstrates that hybrid functional calculations accurately predict the electronic structure of monolayer fullerenes, establishing their viability for water splitting applications.

Findings

All phases have suitable band gaps for water splitting.

Distinct phases exhibit different optical absorption and recombination behaviors.

High carrier mobility supports efficient charge transfer.

Abstract

Photocatalytic water splitting can produce hydrogen in an environmentally friendly way and provide alternative energy sources to reduce global carbon emissions. Recently, monolayer fullerene networks have been successfully synthesized [Hou $\textit{et al., Nature}$ $\textbf{2022}$, 606, 507], offering new material candidates for photocatalysis because of their large surface area with abundant active sites, feasibility to be combined with other 2D materials to form heterojunctions, and the C$_{60}$ cages for potential hydrogen storage. However, efficient photocatalysts need a combination of a suitable band gap and appropriate positions of the band edges with sufficient driving force for water splitting. In this study, I employ semilocal density functional theory and hybrid functional calculations to investigate the electronic structures of monolayer fullerene networks. I find that only the weakly screened hybrid functional, in combine with time-dependent Hartree-Fock calculations to include the exciton binding energy, can reproduce the experimentally obtained optical band gap of monolayer C$_{60}$. All the phases of monolayer fullerene networks have suitable band gaps with high carrier mobility and appropriate band edges to thermodynamically drive overall water splitting. In addition, the optical properties of monolayer C$_{60}$ are studied, and different phases of fullerene networks exhibit distinct absorption and recombination behavior, providing unique advantages either as an electron acceptor or as an electron donor in photocatalysis.