The built-in electric field caused by piezoelectric polarization has emerged as one of the most effective strategies for photoelectrochemical (PEC) water splitting, but is challenged by low piezoelectric polarization efficiency. Herein, we firstly introduce residual stress into CdS through phase transition stress engineering for improving the spontaneous polarization of CdS with a view to revealing the mechanism of the piezoelectric PEC (piezo-PEC) performance of CdS is advanced by the spontaneous polarization. The spontaneous polarization of CdS caused via phase transition residual stress generated built-in electric field to advance carriers separation. Moreover, the spontaneous polarization of CdS is motived a greater potential under external force than hexagonal wurtzite CdS due to the existence of phase transition residual stress, which effectively improves the piezo-PEC performance of CdS. The photocurrent density of miscibility of cubic sphalerite and hexagonal wurtzite CdS (M−CdS) is 0.61 mA/cm² at 1.23 V vs RHE, which is almost 1.79 times of hexagonal wurtzite (H-CdS). In addition, the value of M−CdS photocurrent density is reached 2.12 mA/cm² at 1.23 V vs RHE after ultrasound, which is almost 6.2 times of H-CdS. Our detail work proves that this strategy not only stimulates the piezo-PEC performance of CdS, but also can be extended to other hexagonal wurtzite semiconductor phase transition piezoelectric fields.

由压电极化引起的内置电场已成为光电化学（PEC）水分解最有效的策略之一，但受到压电极化效率低的挑战。在此，我们首先通过相变应力工程将残余应力引入 CdS 以改善 CdS 的自发极化，以期揭示自发极化促进 CdS 的压电 PEC（piezo-PEC）性能的机制。通过相变残余应力引起的 CdS 自发极化产生内置电场以促进载流子分离。此外，由于相变残余应力的存在，CdS 的自发极化在外力作用下比六方纤锌矿 CdS 具有更大的电势，这有效地提高了 CdS 的压电 PEC 性能。立方闪锌矿和六方纤锌矿 CdS (M−CdS) 混溶的光电流密度为 0.61 mA/cm² at 1.23 V vs RHE, which is almost 1.79 times of hexagonal wurtzite (H-CdS). In addition, the value of M−CdS photocurrent density is reached 2.12 mA/cm² at 1.23 V vs RHE after ultrasound, which is almost 6.2 times of H-CdS. Our detail work proves that this strategy not only stimulates the piezo-PEC performance of CdS, but also can be extended to other hexagonal wurtzite semiconductor phase transition piezoelectric fields.