Construction of Au-modified CN-based donor-acceptor system coupled with dual photothermal effects for efficient photoreduction of carbon dioxide

Conversion of CO2 into high value-added fuels through the photothermal effect is an effective approach for utilizing solar energy. In this study, we prepared the CN-based photocatalyst Py-CTN-Au with both donor-acceptor (D-A) system and dual photothermal effects using a simple two-step method involving calcination and photo-deposition. Real-time monitoring with a thermal imaging camera revealed that Py-CTN-Au0.5 achieved a maximum stable temperature of 180 °C, which was approximately 1.2 times higher than that of Py-CTN (155 °C) and 1.9 times higher than that of g-CN (95 °C) under the same reaction conditions. Under the optimized reaction conditions, Py-CTN-Au0.5 exhibited a CO release rate of 30.59 umol g−1 after 4 h of reaction, which was 7.3 times higher than that of pure g-CN (4.18 umol g−1). The D-A system not only facilitated the separation and transformation of charge carriers but also induced a photothermal effect to accelerate the photoreduction of CO2. Additionally, the cocatalyst Au nanoparticles (Au NPs) further enhanced the charge carrier dynamics and photothermal effect by increasing the built-in electric field intensity and localized surface plasmon resonance (LSPR) effect, respectively. The dual photothermal effects resulting from the non-radiative photon conversion of the D-A structure and the Au NPs LSPR effect, along with the enhanced charge carrier dynamics, catalyzed the efficient photoreduction of CO2. DFT simulations were used to confirm the effect of D-A system and Au NPs. In-situ FTIR results demonstrated that the synergistic photothermal effect promoted the formation of the key intermediate species COOH*, which is beneficial for the photocatalytic reduction of CO2. This study provides valuable insights into the multiple photothermal synergistic effects in photocatalytic reactions.