Photothermal Effect of Carbon-Doped Carbon Nitride Synergized with Localized Surface Plasmon Resonance of Ag Nanoparticles for Efficient CO2 Photoreduction

Converting carbon dioxide (CO2) into high-value fuels through the photothermal effect offers an effective approach to enhancing the carbon cycle and reducing the greenhouse effect. In this study, we developed Ag/C-TCN-x, a carbon nitride-based photocatalyst that integrates both photothermal and localized surface plasmon resonance (LSPR) effects. This material was synthesized through a three-step process involving hydrothermal treatment, calcination, and photo-deposition. Real-time infrared thermography monitoring revealed that Ag/C-TCN-2 reached a surface stabilization temperature of approximately 176 °C, which was 1.5 times higher than C-TCN and 2.2 times higher than g-C3N4. Under the same experimental conditions, Ag/C-TCN demonstrated a carbon monoxide (CO) release rate 3.3 times greater than that of pure g-C3N4. The composite sample Ag/C-TCN-2 maintained good photocatalytic activity in five cycling tests. The structural stability of the sample after the cycling tests was confirmed by X-ray diffraction (XRD) test. The unique tubular structure of Ag/C-TCN increased its specific surface area, facilitating enhanced CO2 adsorption. Carbon doping not only triggered the photothermal effect but also accelerated the conversion of carriers. Additionally, the LSPR effect of Ag nanoparticles, combined with carbon doping, optimized charge carrier dynamics and promoted efficient CO2 photoreduction. The CO2 reduction mechanism over Ag/C-TCN was further examined using in situ Fourier Transform Infrared (FT-IR) spectroscopy. This research offers valuable insights into how photothermal and LSPR effects can be harnessed to enhance the efficiency of CO2 photoreduction.