Adsorption and photocatalytic splitting of water on graphitic carbon nitride: a combined first principles and semiempirical study

Overview

Title: 

Adsorption and photocatalytic splitting of water on graphitic carbon nitride: a combined first principles and semiempirical study

Abstract: 

Graphitic carbon nitride, g-C3N4, is a promising organic photo-catalyst for a variety of redox reactions. In order to improve its efficiency in a systematic manner, however, a fundamental understanding of the microscopic interaction between catalyst, reactants and products is crucial. Here we present a systematic study of water adsorption on g-C3N4 by means of density functional theory and the density functional based tight-binding method as a prerequisite for understanding photocatalytic water splitting. We then analyze this prototypical redox reaction on the basis of a thermodynamic model providing an estimate of the overpotential for both water oxidation and H+ reduction. While the latter is found to occur readily upon irradiation with visible light, we derive a prohibitive overpotential of 1.56 eV for the water oxidation half reaction, comparing well with the experimental finding that in contrast to H-2 production O-2 evolution is only possible in the presence of oxidation cocatalysts.

Authors: 

Jonas Wirth, Rainer Neumann, Markus Antonietti, Peter Saalfrank

DOI: 

Journal: 

Physical Chemistry Chemical Physics

Year: 

2014

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