Electrospun Cd_0.3Zn_0.7S/PVDF/PAN nanofibers: Synergistic enhancement of photocatalytic hydrogen evolution via piezoelectric polarization and carbon dot-mediated electronic modulation

The practical application of photocatalytic hydrogen evolution is severely hindered by the low intrinsic activity and poor recyclability of conventional photocatalysts. Moreover, single-factor optimization strategies are often insufficient to meet the complex demands of efficient and stable solar-to-hydrogen conversion. To address these limitations, we propose a synergistic regulation strategy by integrating piezoelectric polarization and carbon dot (CD)-mediated electronic modulation into a nanofiber-based Cd_0.3Zn_0.7S/polyvinylidene fluoride (PVDF)/polyacrylonitrile (PAN) (CPP) photocatalyst system. The incorporation of CDs not only enhances visible light absorption and accelerates carrier transport, but also induces the β-phase transition in PVDF, significantly strengthening its piezoelectric response. Under mechanical stirring, the generated piezoelectric field promotes the spatial separation and interfacial migration of photogenerated carriers. More importantly, the synergistic “piezoelectrically coupled CDs” mechanism constructs an internal electric field that amplifies the charge separation efficiency. As a result, the optimized C_7.5PP-0.125CDs photocatalyst achieves a hydrogen evolution rate of 49.4 mmol·g⁻¹·h⁻¹, 3.2 times higher than pristine Cd_0.3Zn_0.7S. The piezoelectric effect alone enhances the rate by 31.7%, whereas the combined strategy results in an 82.3% improvement.