Carbon hollow spheres as cocatalyst of Cu-doped TiO₂ nanoparticles for improved photocatalytic H₂ generation

Abstract

The reasonable employment of cocatalyst in photocatalysis can effectively promote the photocatalytic H₂ production activity. In this study, carbon hollow spheres (C), as a good conductive nonmetallic material, have been utilized as a novel cocatalyst and a matrix for loading the Cu-doped-TiO₂ nanoparticles by a successive hydrothermal method and metal molten salt method. The Cu-doped-TiO₂ nanoparticles were tightly anchored on the surface of carbon hollow sphere to form a zero-dimensional/three dimensional (0D/3D) Cu-doped-TiO₂/C heterojunction. The optimal Cu-doped-TiO₂/C heterojunction demonstrated greatly enhanced photocatalytic H₂ generation activity (14.4 mmol·g⁻¹·h⁻¹) compared with TiO₂ (0.33 mmol·g⁻¹·h⁻¹) and TiO₂/C (0.7 mmol·g⁻¹·h⁻¹). The performance improvement was mainly due to the synergistic effect of carbon hollow sphere cocatalyst and Cu-doping, the Cu-doping in TiO₂ nanoparticles can minimize charge recombination and enhance the available photoexcited electrons, while the 3D carbon hollow spheres can act as electron traps to accelerate the charge separation and offer abundant active sites for solar water splitting reaction.

Graphical abstract

摘要

在光催化过程中合理地使用助催化剂可以有效地促进光催化产氢的活性。在本研究中, 通过水热法和金属熔盐法制备了一种以碳空心球 (C), 一种良好的导电非金属材料, 作为助催化剂及生长基体负载的Cu-掺杂的TiO2纳米颗粒新型光催化材料。铜掺杂TiO2纳米颗粒被紧密地固定在碳空心球的表面, 形成了0D/3D的Cu掺杂的TiO2/C异质结。与TiO₂ (0.33 mmol·g-1·h-1) 和TiO₂/C (0.7 mmol·g-1·h-1) 相比, 最佳的Cu掺杂的TiO2/C异质结显示出更好的光催化产氢活性 (14.4 mmol·g-1·h-1)。光催化性能提高主要归因于碳空心球体的助催化和Cu掺杂的协同作用, TiO₂纳米颗粒中的Cu掺杂可以最大限度地减少电荷重组, 提高可用的光激发电子, 而三维碳空心球体可以作为电子陷阱, 加速电荷分离, 为太阳能水分离反应提供丰富的活性位点。