Thickness Control of BiOIO3 Enables Polarization Enhancement To Promote Carrier Separation and Pyro-PEC Performance

Pyroelectric polarization is considered to be one of the effective ways to promote carrier separation and improve the capacity of PEC water splitting. In this paper, we prepared a BiOIO3 catalyst by a one-pot hydrothermal method and investigated the growth process of BiOIO3, based on which HNO3 and NaOH were used to cause BiOIO3 to grow selectively along the (040) direction, and the regulation mechanism was analyzed so as to improve the pyroelectric polarization intensity of BiOIO3. Under the dual excitation of light and cold–hot cycles, the optimal thickness range of BiOIO3 nanoplate (40–50 nm) exhibits the highest photocurrent density of 0.134 μA/cm2 at 1.23 V compared with the reversible hydrogen electrode (RHE), which is 1.6 times higher than that of the nanosheet with a thickness of 20–30 nm. A series of experimental results show that the high performance is due to suitable thickness modulation which not only enhances the polarization intensity and thus reduces the chemical reaction barrier but also facilitates the charge separation and transfer. This study provides a different way of thinking for the development of the field of pyro-photo-electric catalysis on the basis of enhanced pyroelectric polarization.