Yu Jiaguo, Wang Ke, Xiao Wei, Cheng Bei
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, P. R. China.
Phys Chem Chem Phys. 2014 Jun 21;16(23):11492-501. doi: 10.1039/c4cp00133h. Epub 2014 May 7.
Photocatalytic reduction of CO2 into renewable hydrocarbon fuels is an alternative way to develop reproducible energy, which is also a promising way to solve the problem of the greenhouse effect. In this work, graphitic carbon nitride (g-C3N4) was synthesized by directly heating thiourea at 550 °C and then a certain amount of Pt was deposited on it to form g-C3N4-Pt nanocomposites used as catalysts for photocatalytic reduction of CO2 under simulated solar irradiation. The main products of photocatalysis were CH4, CH3OH and HCHO. The deposited Pt acted as an effective cocatalyst, which not only influenced the selectivity of the product generation, but also affected the activity of the reaction. The yield of CH4 first increased upon increasing the amount of Pt deposited on the g-C3N4 from 0 to 1 wt%, then decreased at 2 wt% Pt loading. The production rates of CH3OH and HCHO also increased with the content of Pt increasing from 0 to 0.75 wt% and the maximum yield was observed at 0.75 wt%. The Pt nanoparticles (NPs) could facilitate the transfer and enrichment of photogenerated electrons from g-C3N4 to its surface for photocatalytic reduction of CO2. At the same time, Pt was also used a catalyst to promote the oxidation of products. The transient photocurrent response further confirmed the proposed photocatalytic reduction mechanism of CO2. This work indicates that the deposition of Pt is a good strategy to improve the photoactivity and selectivity of g-C3N4 for CO2 reduction.
将二氧化碳光催化还原为可再生碳氢燃料是开发可再生能源的一种替代方法，也是解决温室效应问题的一种有前景的途径。在这项工作中，通过在550℃直接加热硫脲合成了石墨相氮化碳（g-C3N4），然后在其上沉积一定量的铂以形成g-C3N4-Pt纳米复合材料，用作模拟太阳光照下二氧化碳光催化还原的催化剂。光催化的主要产物为CH4、CH3OH和HCHO。沉积的铂作为有效的助催化剂，不仅影响产物生成的选择性，还影响反应活性。当沉积在g-C3N4上的铂含量从0增加到1 wt%时，CH4的产率首先增加，然后在铂负载量为2 wt%时下降。CH3OH和HCHO的生成速率也随着铂含量从0增加到0.75 wt%而增加，在0.75 wt%时观察到最大产率。铂纳米颗粒（NPs）可以促进光生电子从g-C3N4转移并富集到其表面以进行二氧化碳的光催化还原。同时，铂也用作促进产物氧化的催化剂。瞬态光电流响应进一步证实了所提出的二氧化碳光催化还原机理。这项工作表明，铂的沉积是提高g-C3N4光催化还原二氧化碳的光活性和选择性的一种良好策略。
