Pyroelectric effects in CdS phase junctions for dual-enhanced photocatalytic hydrogen production

Abstract

Hexagonal cadmium sulfide (CdS) with noncentro-symmetric structure can spontaneously polarize under the condition of temperature change to produce piezoelectric and pyroelectric effects. However, its pyroelectric effect has not been used effectively to enhance photocatalytic hydrogen (H₂) production. Herein, we present a strategy of fast construction of CdS phase junctions derived from partial phase transition at different annealing temperatures. Benefitting from the generation of a cubic phase from hexagonal CdS, the photocatalytic H₂ production is greatly enhanced via pyroelectric effects. Under thermal cycling between 20 °C and 40 °C, the CdS phase junction exhibits an effective improvement of H₂ evolution activity of 98.5 μmol mg⁻¹ h⁻¹, superior to that of hexagonal CdS by nearly 10 times, owing to the superposition of two built-in electric fields from the phase junction and temperature oscillation. Overall, the fast construction of the CdS phase junction via local phase transition is a simple, compatible, and impactful strategy for pyroelectric effect-enhanced photocatalysis.