In situphoto-derived MnOOH collaborating with Mn2Co2C@C dual co-catalysts boost photocatalytic overall water splitting

Photocatalytic (PC) overall water splitting (OWS) is considered an ideal method for solar-to-fuel conversion, though its practical application is greatly limited by the loading of noble-metal co-catalysts. It is, therefore, of great significance to explore alternate non-noble-metal co-catalysts. Herein, a novel non-precious metal Mn2Co2C@C/Mn(2)N(0.86)composite (denoted as MCMN), composed of Mn(2)N(0.86)and N-doped graphitized carbon wrapped Mn2Co2C nanoparticles, was fabricated and then used to modify photocatalysts, such as g-C(3)N(4)and SrTiO(3)for the construction of MCMN/g-C(3)N(4)and MCMN/SrTiO(3)composite photocatalysts by a mechanical grinding method. When they were used for PC OWS under UV-Vis light irradiation, in the initial stage, the Mn(2)N(0.86)in MCMN was hydrolyzed, and novel non-precious metal MnOOH and Mn2Co2C@C (MC) dual cocatalysts were photo-derived to growin situon the surfaces of photocatalysts. In the new kind of MC/g-C3N4/MnOOH PC system, the metallic MC acts as a co-catalyst for H(2)generation, effectively trapping photoelectrons and accelerating H(2)evolution reaction; meanwhile, MnOOH acts as a co-catalyst for O(2)generation, favoring the adsorption of water molecules on the surface to boost the O(2)evolution reaction. Consequently, the optimized MC/g-C3N4/MnOOH showed a prominent H(2)evolution rate of 8.876 mu mol h(-1)for PC OWS, even higher than that of g-C(3)N(4)loaded with 1 wt% Pt, and the corresponding AQE reached 2.54% and 1.45% at 400 and 420 nm, respectively. A similar promotion was also obtained on the SrTiO(3)photocatalyst, demonstrating the versatility of this composite. This work provides a new avenue for the construction of novel noble-metal-free PC systems.