All measurements were done using the same sample and substrate as used for hydrogen evolution reaction and stearic acid degradation tests. For hydroxyl radical trapping experiments, the thin film was inserted in 20 mL of TA (0.5 mM) and NaOH (2 mM) and illuminated with simulated solar light (100 mWcm -2 ). The fluorescent emission intensity of 2hydroxyterephthalic acid was detected with λmax at 425 nm under the excitation at 315 nm using a Shimadzu RF-6000 spectrofluorometer, equipped with a Xe lamp. For both excitation and