Synthesis of crystalline BaZrO3 thin films over preferred-oriented ZrN by a hydrothermal-galvanic couple method for photoelectrochemical evaluations

Abstract

Crystalline barium zirconate (BaZrO 3 ; BZO) films which could be applied to photoelectrochemical cells and fuel cells were synthesized by a hydrothermal-galvanic couple (HT–GC) method using preferred-oriented ZrN thin-film electrodes. The HT–GC synthesis was carried out at 90°C in alkaline solutions. Substantial galvanic currents were detected without applying any external power sources throughout the synthesis. X-ray diffraction patterns reveal that BZO films with different crystallinities were achieved by such a facile synthesis. Moreover, the BZO films that grew on close-packed (200)-preferred oriented ZrN underlayer exhibited higher crystallinity and growth rates than on the (111)-preferred oriented ZrN. The obtained BZO films exhibited fast on-off photoelectrochemical responses while the BZO films with higher crystallinity over the (200)-ZrN possessed better photoelectrochemical responses. • Crystalline BaZrO3 films could be synthesized on ZrN by a hydrothermal-galvanic couple method • Crystallinity and photoelectrochemical performance of the films were tailored through ZrN • Galvanic effects were enhanced by using (200)-oriented ZrN rather than (111) oriented ZrN • Higher crystallinity of the films could be achieved by a more close-packed (200)-ZrN • Better and fast on-off photoelectrochemical responses of the films were obtained by (200)-ZrN