Enhancement Strategy of Photoelectrocatalytic Activity of Cobalt-Copper Layer Double Hydroxide toward Methanol Oxidation: Cerium Doping and Modification with Porphyrin.

Designing durable, high-active, and low-cost noble-metal-free photoelectrocatalysts for methanol electrooxidation is highly demanded but remains a challenge. Herein, the photoelectrocatalytic activity of cobalt-copper layer double hydroxide (CoCu-LDH) for methanol oxidation reaction (MOR) in the alkaline media under light was remarkably enhanced by cerium (Ce) doping and further by 5,10,15,20-tetrakis(4-carboxylphenyl)porphyrin (TCPP) modification. TCPP/Ce-CoCu-LDH exhibits a remarkable mass activity of 1788.2 mA mg-1 in 1 mol L-1 KOH with 1 mol L-1 methanol under light, which is 2.3 and 1.8 times higher than that of CoCu-LDH (782.2 mA mg-1) and Ce-CoCu-LDH (987.4 mA mg-1). The UV-vis diffuse reflectance spectra and photoluminescence emission spectra reveal that TCPP/Ce-CoCu-LDH can effectively utilize the visible light and inhibit the electron-hole pairs' recombination because of the introduction of porphyrin. Furthermore, more active sites and the greater electrical conductivity of TCPP/Ce-CoCu-LDH also contributed to the high photoelectrocatalytic activity. Thus, TCPP/Ce-CoCu-LDH can be used as a low-cost alternative for Pt-based catalyst toward MOR.