NiS Cocatalyst-Modified ZnIn2S4 as Ohmic-Junction Photocatalyst for Efficient Conversion of CO2

Improved photogenerated carrier separation efficiency is of importance for improving photocatalytic activity. Herein, the photocatalytic CO2 reduction of a 3D/0D ZnIn2S4/NiS ohmic-junction photocatalyst under simulated sunlight is studied. The ZnIn2S4-2%NiS sample has the best excellent photoreduction CO2 performance facilitated by triethanolamine (TEOA) reagents, the ZnIn2S4-2%NiS sample with a CO yield of 12.63 mu mol g(-1) h(-1), which is two times that for pure ZnIn2S4 (6.37 mu mol g(-1) h(-1)). It is demonstrated that NiS nanoparticles not only improve the efficiency of electron generation and charge separation by constructing a tight contact ohmic-junction, but also act as a cocatalyst to extend the photoreaction range and lower the reaction barrier, which effectively accelerates the photocatalytic reduction reaction. Additionally, the 3D structure of ZnIn2S4 has an excellent specific surface area that facilitates the dispersion of NiS. The generation, separation, and migration of photogenerated electron holes are studied from the kinetics perspective through transient photocurrent response, linear sweep voltammetry curve and photoluminescence spectroscopy. In situ Fourier transform infrared spectroscopy is applied to study the CO2 photoreduction process. Herein, the important role of cocatalyst and ohmic-junction in improving photocatalytic activity is revealed and a new idea for the construction of efficient photocatalysts is provided.