Preparation and photocatalytic performance of silver-modified and nitrogen-doped TiO2 nanomaterials with oxygen vacancies

The photocatalysis of titanium dioxide (TiO2) exerts excellent degradation performance against contaminants in the environment. However, it prefers to absorb ultraviolet light rather than visible light, which significantly constrains its widespread use under visible light. Here, we prepared oxygen vacancy-containing TiO2via Ag-modification and N-doping. The utilization of visible light for phenol degradation was significantly enhanced by Ag/N co-doping. The characterization results showed a shuttle-like material coupled with multiple oxygen vacancies, and a well-designed experiment demonstrated that the Ti : N : Ag ratio of 1 : 0.45 : 0.32 presented optimal performance for phenol degradation. The batch experiment results also proved the modified TiO2 as a potent photocatalyst against phenol degradation with an 80.8% degradation efficiency within 5 hours under visible light and with a 99.3% degradation efficiency within 2 hours under ultraviolet light. What is more, we also demonstrated that hydroxyl radical was the mainly effective radical in the mineralization of phenol and put forward a possible degradation pathway based on the observed intermediates. Lastly, the cycling tests indicated that the proposed photocatalyst is durable with a fair phenol degradation ability after recycling 5 times.