Single Atom (Pd/Pt) Supported on Graphitic Carbon Nitride as an Efficient Photocatalyst for Visible-Light Reduction of Carbon Dioxide

TLDR

Reducing carbon dioxide to hydrocarbon fuel with solar energy is significant for high‑density solar energy storage and carbon balance. This study uses density functional theory to investigate single‑atom palladium and platinum supported on graphitic carbon nitride as photocatalysts for CO₂ reduction. The single metal atoms act as active sites while g‑C3N4 supplies hydrogen atoms for the reduction reaction. The Pd/g‑C3N4 and Pt/g‑C3N4 photocatalysts show excellent CO₂ reduction activity, with Pd/g‑C3N4 favoring formic acid (0.66 eV barrier) and Pt/g‑C3N4 favoring methane (1.16 eV barrier), and both systems exhibit enhanced visible‑light absorption, opening a new avenue for renewable energy supply.

Abstract

Reducing carbon dioxide to hydrocarbon fuel with solar energy is significant for high-density solar energy storage and carbon balance. In this work, single atoms of palladium and platinum supported on graphitic carbon nitride (g-C3N4), i.e., Pd/g-C3N4 and Pt/g-C3N4, respectively, acting as photocatalysts for CO2 reduction were investigated by density functional theory calculations for the first time. During CO2 reduction, the individual metal atoms function as the active sites, while g-C3N4 provides the source of hydrogen (H*) from the hydrogen evolution reaction. The complete, as-designed photocatalysts exhibit excellent activity in CO2 reduction. HCOOH is the preferred product of CO2 reduction on the Pd/g-C3N4 catalyst with a rate-determining barrier of 0.66 eV, while the Pt/g-C3N4 catalyst prefers to reduce CO2 to CH4 with a rate-determining barrier of 1.16 eV. In addition, deposition of atom catalysts on g-C3N4 significantly enhances the visible-light absorption, rendering them ideal for visible-light reduction of CO2. Our findings open a new avenue of CO2 reduction for renewable energy supply.