1,2,4-Triazole-Based Approach to Noble-Metal-Free Visible-Light Driven Water Splitting over Carbon Nitrides

MoS2/Co2O3/poly(heptazine imide) composite photocatalysts which are active in both noble-metal-free water reduction and water oxidation half reactions upon irradiation with visible light were synthesized by a one-step procedure. Here, the LiCl/KCl eutectic melt was used as a high-temperature solvent; 3-amino-1,2,4-triazole-5-thiol simultaneously acts as a carbon nitride precursor, sulfur source, and reducing agent for Mo5+, while MoCl5 was added as a metal source for MoS2 nanoparticles being active centers for the water reduction reaction. Water oxidation centers could be created using the rich complexation chemistry of 1,2,4-triazoles. Namely, cobalt species were introduced into carbon nitride network using Co3[3,5-diamino-1,2,4-triazole]6 complex as a dopant, prepared in a separate step. The developed method enables one to control the cocatalysts’ loading and tune the dimensions of MoS2 NPs. The materials reported here show 10% of the efficiency of a reference Pt/mesoporous graphitic carbon nitride composite in hydrogen evolution, and half of the performance of the reference Co3O4/S-doped carbon nitride material, prepared by multistep synthesis, in oxygen evolution, however, in one and the same system.