Quantum effect and Mo–N surface bonding states of α-MoC1−x modified carbon nitride for boosting photocatalytic performance

Photocatalytic degradation of pharmaceuticals in the aquatic environment is considered a promising strategy to address water pollution. In this study, a novel photocatalyst was constructed by decorating g-C3N4 (CN) with α-MoC1−x quantum dots (α-MoC1−x-QDs) through a facile calcination method. The catalyst showed enhanced tetracycline (TC) degradation performance under visible light. The unique Mo–N surface bonding states and quantum effect leading to superior TC degradation activity (89.1%) compared to pure CN (21.8%) were reported and revealed. More importantly, the mechanism for the significant enhancement of photocatalytic activity of the catalyst was investigated by DFT (density functional theory) calculations and photo-electrochemistry measurements. The results confirmed that the effect of α-MoC1−x-QDs on CN improved the light absorption capacity obviously, and the Mo–N surface bonding states accelerated the charge migration from CN to α-MoC1−x-QDs. Moreover, the TC degradation pathway, intermediates and photogenerated carrier transfer behaviors were also discussed in depth. This research provides a new strategy for the construction of noble-metal-free co-catalyst/semiconductor composite materials in the photocatalytic degradation of antibiotics.