Highly efficient sunlight-driven LSPR-enhanced core-shell Ag dendrite/ g-C₃N₄ composite photocatalysts

Noble metal nanostructures with localized surface plasmon resonance (LSPR) effect can be employed to enhance the light absorption ability of photocatalysts. However, it has been a challenge to control the size and morphology of noble metal nanostructures to manipulate the LSPR wavelength and improve the performance of photocatalysts. Herein, an Ag dendrite (AgD) composed of Ag nanorods with different sizes was facilely constructed by a displacement reaction, and sunlight-driven LSPR-enhanced core-shell AgD/g-C3N4 composite photocatalysts (AgD-CN) were synthesized by thermal polymerizing mixtures of melamine and different amounts of AgD. This core-shell AgD-CN improved the stability of AgD and made full use of the near-field enhancement effect of AgD's LSPR, resulting in a broad light absorption band. AgD-CN-15 showed the highest photogenerated electron-hole pair separation rate and the best photocatalytic performance when the addition amount of AgD was 3 wt%. The degradation rate of RhB by AgD-CN-15 reached 95.20% after sunlight irradiation for 60 min, and its reaction rate constant was 5.2 times that of the pristine g-C3N4. Moreover, OH, h(+) and O-2(-) were found to be the main active species. AgD is easy to prepare and can broaden the light absorption wavelength range and significantly enhance light absorption ability of photocatalysts, which provides a new method to improve the performance of LSPR-enhanced photocatalysts.