Photocatalytic Dissociation of CH 3 OH on ZnO(0001) Surface

Photocatalysis of CH $_3$ OH on the ZnO(0001) surface has been investigated by using temperature-programmed desorption (TPD) method with a 266 nm laser light. TPD results show that part of the CH $_3$ OH adsorbed on ZnO(0001) surface are in molecular form, while others are dissociated. The thermal reaction products of H $_2$ , CH $_3$ $^\cdot$ , H $_2$ O, CO, CH $_2$ O, CO $_2$ and CH $_3$ OH have been detected. Experiments with the UV laser light indicate that the irradiation can promote the dissociation of CH $_3$ OH/CH $_3$ O $^{\cdot}$ to form CH $_2$ O, which can be future converted to HCOO $^-$ during heating or illumination. The reaction between CH $_3$ OH $_{\text{Zn}}$ and OH $_{\text{ad}}$ can form the H $_2$ O molecule at the Zn site. Both temperature and illumination promote the desorption of CH $_3$ $^{\cdot}$ from CH $_3$ O $^{\cdot}$ . The research provides a new insight into the photocatalytic reaction mechanism of CH $_3$ OH on ZnO(0001).