Enhancing the macroscopic polarization of CdS for piezo-photocatalytic water splitting

• Published in: Nano energy 2021-12, Vol.90, p.106635, Article 106635
• Main Authors: Zhang, Meiyu, Nie, Siyang, Cheng, Tao, Feng, Yu, Zhang, Chenchen, Zheng, Lei, Wu, Liang, Hao, Weichang, Ding, Yong
• Format: Article
• Language: English
• Subjects: CdS phase junction; Dipole moment; H2 evolution; Macroscopic polarization; Piezo-photocatalytic
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2021.106635

Piezo-photocatalytic hydrogen production from water splitting is emerging as a promising way to generate renewable energy, but is challenged by low efficiency and ambiguous understanding of mechanisms. Herein, the CdS phase junction (H/C-CdS) with interfacial structural distortion is applied for prominent piezo-photocatalytic H2 evolution for the first time. Density functional theory (DFT) and second harmonic generation (SHG) demonstrate that the superior macroscopic polarity in H/C-CdS originates from the distortion of CdS4 tetrahedron units at the interface between hexagonal CdS (H-CdS) and cubic CdS (C-CdS). The obvious enhanced macroscopic polarity of H/C-CdS largely boosts the separation of photogenerated electrons and holes with the elimination of the electrostatic screening produced in CdS phase junction. An encouraging piezo-photocatalytic H2 evolution rate of 3.19 mmol·g−1·h−1 is delivered by H/C-CdS in pure water in the absence of any co-catalyst, which is 1.4 and 5.3 times higher than those of H-CdS (2.31 mmol·g−1·h−1) and C-CdS (0.59 mmol·g−1·h−1), respectively. Additionally, the value-added oxidation product H2O2 is produced in piezo-photocatalysis. This work firstly discloses macroscopic polarization enhancement induced by phase junction system on improvement of piezo-photocatalytic H2 evolution of CdS. The construction of phase junction CdS is utilized for piezo-photocatalytic H2 evolution in pure water by collecting solar and mechanical energy. The tetrahedral distortion in phase junction CdS enhances the macroscopic polarization of hexagonal CdS and accelerates the separation of photoinduced charges, resulting in prominent piezo-photocatalytic H2 evolution performance. [Display omitted] •The construction of phase junction CdS enhances the macroscopic polarization of hexagonal CdS.•Density functional theory (DFT) confirmed the increased dipole moment of phase junction CdS.•The macroscopic polarization enhancement in phase junction CdS boosts the separation of photoinduced charges.•An encouraging piezo-photocatalytic H2 evolution rate of 3.19 mmol·g−1·h−1 is achieved by phase junction CdS.