Hu Cheng, Chen Fang, Wang Yonggang, Tian Na, Ma Tianyi, Zhang Yihe, Huang Hongwei
Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing, 100083, China.
Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing, 100094, China.
Adv Mater. 2021 Jun;33(24):e2101751. doi: 10.1002/adma.202101751. Epub 2021 May 8.
Utilizing mechanical energy to produce hydrogen is emerging as a promising way to generate renewable energy, but is challenged by low efficiency and scanty cognition. In this work, graphitic carbon nitride (g-C N ) with an atomically thin sheet-like structure is applied for prominent piezocatalytic and photo-enhanced piezocatalytic H production. It is revealed that the anomalous piezoelectricity in g-C N originates from the strong in-plane polarization along the a-axis, contributed by the superimposed polar tri-s-triazine units and flexoelectric effect derived from the structured triangular cavities, which provides powerful electrochemical driving force for the water reduction reaction. Furthermore, the photo-enhanced charge transfer enables g-C N nanosheets to reserve more energized polarization charges to fully participate in the reaction at the surface reactive sites enriched by strain-induced carbon vacancies. Without any cocatalysts, an exceptional photo-piezocatalytic H evolution rate of 12.16 mmol g h is delivered by the g-C N nanosheets, far exceeding that of previously reported piezocatalysts and g-C N photocatalysts. Further, high pure-water-splitting performance with production of the value-added oxidation product H O via photo-piezocatalysis is also disclosed. This work not only exposes the potential of g-C N as a piezo-semiconductor for catalytic H evolution, but also breaks a new ground for the conversion of solar and mechanical energy by photomediated piezocatalytic reaction.
利用机械能制氢正成为一种有前景的可再生能源生产方式，但面临着效率低和认知不足的挑战。在这项工作中，具有原子级薄片结构的石墨相氮化碳（g-C₃N₄）被用于显著的压电催化和光增强压电催化产氢。研究表明，g-C₃N₄中的异常压电性源于沿a轴的强面内极化，这是由叠加的极性三嗪单元和结构化三角形空腔产生的挠曲电效应共同作用的结果，为水还原反应提供了强大的电化学驱动力。此外，光增强的电荷转移使g-C₃N₄纳米片能够保留更多的激发极化电荷，以充分参与由应变诱导的碳空位富集的表面反应位点处的反应。在没有任何助催化剂的情况下，g-C₃N₄纳米片实现了12.16 mmol g⁻¹ h⁻¹的优异光压电催化析氢速率，远远超过了先前报道的压电催化剂和g-C₃N₄光催化剂。此外，还揭示了通过光压电催化生产增值氧化产物H₂O₂的高纯水分解性能。这项工作不仅揭示了g-C₃N₄作为催化析氢的压电半导体的潜力，也为通过光介导的压电催化反应将太阳能和机械能转化开辟了新的途径。
