CuGaO2/TiO2 heterostructure nanosheets: Synthesis, enhanced photocatalytic performance, and underlying mechanism

Effective separation and fast transport of photogenerated carriers are vital links determining the photocatalytic performance. Heterostructure constructed by two complementary semiconductors is a feasible strategy to achieve this goal. By one-pot hydrothermal method, 0D-TiO 2 nanoparticles are loaded onto 2D-CuGaO 2 nanosheets, forming a mixed dimension, closely combined heterostructure. The photocurrent density of CuGaO 2 /TiO 2 heterostructure is ∼16.6 μA/cm 2 , which is 1.24 times higher than that of pristine CuGaO 2 nanosheets (∼13.4 μA/cm 2 ) and 15 times higher than that of TiO 2 (∼1.1 μA/cm 2 ). In the tetracycline hydrochloride degradation experiment, the degradation efficiency of tetracycline hydrochloride by CuGaO 2 /TiO 2 heterostructure reached 99% within 90 min, which was 1.2 times the degradation efficiency of CuGaO 2 nanoparticles (82%) and 20.2 times the degradation rate of TiO 2 (4.9%). A series of experimental characterizations combined with density functional theory calculations revealed that it is the built-in electric field in the CuGaO 2 /TiO 2 interface region that drives the photogenerated electron–hole pairs to travel in the opposite direction, thus inhibiting their recombination. Furthermore, the energy band offset of the CuGaO 2 /TiO 2 interface makes it easier for the photogenerated holes and electrons to gather onto the valence band of the CuGaO 2 nanosheets and the conduction band of the TiO 2 nanoparticles, respectively. Therefore, appropriate interface lattice matching, suitable configuration of band gap and band edge positions, and strong opposite drive of interface electric field enable CuGaO 2 /TiO 2 heterostructure to achieve wide spectral response and effective separation of photogenerated electron–hole pairs at the same time.