Operando SERS self-monitoring photocatalytic oxidation of aminophenol on TiO2 semiconductor

The utilization of the fingerprint spectrum for the operando monitoring of a photocatalytic process is extremely desired to accurately understand the reaction mechanism but long remains challenging. Here, ordered macroporous TiO2 that is concomitantly photocatalytically active and high surface-enhanced Raman scattering (SERS) sensitive was unprecedentedly employed to self-track the photocatalytic reaction using the oxidation of p-aminothiophenol (PATP) as the model. The photocatalytic degradation under 532 nm laser irradiation initiated from the formation of the azo compound was explicitly revealed by finely resolved SERS spectra. More importantly, the decomposition rates of different bonds including NN, CS and CC were respectively determined, following a first-order kinetics process with the rates in the range of 2.1–2.7 × 10−3 s−1. Meanwhile, this self-monitoring strategy also provides an opportunity for gaining an insight into the effect of photothermal catalysis on selective formation of the azo compound.