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Efficient charges separation and transfer are considered to be the key factors to achieve high efficiency photoelectric catalysis. Herein, we proposed that the internal potential difference and the macroscopic polarization field of the homotype BaTiO3/CdS pyroelectric heterojunction can adjust the photoelectric catalytic performance to achieve degradation of methylene blue (MB) and rhodamine B (RhB) dyes. Under 20–50 °C hot–cold cycles, light and external bias, the catalytic rate of BaTiO3/CdS for MB is 4.82×10−2 min−1, which is 1.29 times and 1.36 times higher than photoelectric catalytic rates of BaTiO3/CdS (3.74×10−2 min−1) and BaTiO3 (2.15×10−2 min−1) alone, respectively. In addition, the catalytic rate of BaTiO3/CdS for RhB is 3.07×10−2 min−1, which is 1.41 times and 1.28 times higher than photoelectric catalytic rates of BaTiO3/CdS (2.18×10−2 min−1) and BaTiO3 (1.45×10−2 min−1) alone, respectively. The improvement of catalytic efficiency is due to the generation of pyrogenerated and photogenerated carriers, and the macroscopic polarization field and the potential difference at the BaTiO3/CdS heterojunction interface can enhance the separation and transfer of charge. This study confirms that the homotype heterojunction based on the pyroelectric effect can use solar/thermal energy to achieve efficient photoelectric catalysis. This provides a reference for the design and development of new and efficient electrodes in the field of photoelectric catalysis.

The low utilization of light and the severe recombination of charge carriers have always restricted the development of photoelectric catalysis. In this work, the photoelectric catalytic performance is tuned by doping Sr in BaTiO 3 pyroelectric material and simultaneously introducing oxygen vacancies to form double-type defects, combined with pyroelectric polarization. Under the light and 20-50 °C cold-heat cycle, the current density of Ba 0.7 Sr 0.3 TiO 3-X reaches the maximum of 0.92 mA • cm À 2 , which is higher than the current density of Ba 0.7 Sr 0.3 TiO 3-X under only light (0.69 mA • cm À 2 ). Under light alone, the current density of Ba 0.7 Sr 0.3 TiO 3-X is higher than that of BaTiO 3 (0.19 mA • cm À 2 ) and Ba 0.7 Sr 0.3 TiO 3 (0.44 mA • cm À 2 ). This is because the incorporation of Sr can introduce the Fermi level, improve the utilization rate of solar energy, and improve the pyroelectric polarization effect with volume shrinkage, and promote the separation and transfer of carriers. Oxygen vacancies can be used as reactive centers for excited electrons to suppress the recombination of excited electron-hole pairs. Furthermore, the generation of photogenerated and pyrogenerated carriers increases the overall carrier concentration. This provides ideas for the modification of traditional photoelectrodes for photoelectric catalysis water splitting.