Constructing photothermal core-shell photonic crystal structure for efficient photocatalytic CO₂ reduction

To solve the problems of low utilization over the solar spectrum, elevating the photon absorption efficiency and exploiting long-wavelength photons are of great significance. Herein, a CdSe/polydopamine(PDA)@SiO₂ core–shell opal photonic crystal structure with excellent photothermal effect and photon absorption was fabricated for the first time. The photonic bandgap (PBG) effect and the slow photon effect of the photonic crystal structure helps the absorbing of photons and the photothermal effect of PDA coating shells provides higher reacting temperature for photocatalysis. Consequently, the S2P0 sample (without PDA coating) whose PBG is consistent with the absorption edge of CdSe photocatalyst exhibits a three times higher CO₂ reduction efficiency. Benefited from the photothermal effect of PDA, the S2P20 sample (20% PDA coating) shows a 4.77-fold efficiency than the blank sample, proving the reliability of the design. Moreover, the PDA shells enhance the adhesion for robust photonic crystal films and show other applications in fields like textiles. This work demonstrates a synergistic utilization of photothermal effect and photonic crystal structure for efficient photocatalytic CO₂ reduction and revealing more potential applications.