摘要
The photoreduction of CO_(2)to achieve high-value-added hydrocarbons under simulated sunlight irradiation is advantageous,but challenging.In this study,a series of MgO and Au nanoparticle-co-modified g-C_(3)N_(4)photocatalysts were synthesized and subsequently applied for the photocatalytic reduction of CO_(2)with H2O under simulated solar irradiation.The best photocatalytic performance was demonstrated by the Au and 3%MgO-co-modified g-C_(3)N_(4)photocatalysts with CO,CH_(4),CH3OH,and CH3CHO yields of 423.9,83.2,47.2,and 130.4μmol/g,respectively,in a 3-h reaction.We investigated the effects of MgO and Au as cocatalysts on photocatalytic behaviors,respectively.The characterizations and experimental results showed that the enhanced photocatalytic activity was due to the synergistic effect among the components of the ternary photocatalyst.The cocatalyst MgO can activate CO_(2)(adsorbed at the interface between the MgO and Au particles),and the Mg-N bonds formed in the MgO-CN nanosheets played an important role in the charge transfer.Meanwhile,the Au particles that were modified into MgO/g-C_(3)N_(4)can increase the absorption of visible light via the surface plasmon resonance effect and further reduce the activation energies of the photoreduction of CO_(2)using H2O.This study provided an effective method for the modification of traditional primary photocatalysts with promising performance for photocatalytic CO_(2)reduction.
光催化CO_(2)还原制备太阳燃料被广泛关注并逐渐形成研究热点,该过程利用可再生清洁能源太阳能,在低温低压的温和条件下驱动CO_(2)还原制备CO、CH_(4)、CH3OH等燃料气体或者高附加值的碳氢化合物.半导体光催化剂能够将清洁的太阳能有效地转化为化学能,其中,g-C_(3)N_(4)由于其成本低、毒性低、稳定性高和带隙窄等优点,被广泛应用于光催化领域.然而,纯g-C_(3)N_(4)具有光利用效率低和光生电子-空穴复合率高的缺点,导致光催化活性相对较低.因此,需要对g-C_(3)N_(4)进行修饰改性来提高其光催化性能.一方面,MgO具有强大的CO_(2)吸附能力,可用于修饰半导体以提高光催化还原CO_(2)的反应活性.另一方面,助催化剂尤其是贵金属,不仅能够捕获电子以提高光生电子-空穴对的分离效率,而且还能提供反应的活性位点.本文通过沉淀和煅烧法制备了不同复合量的MgO-g-C_(3)N_(4)催化剂,同时负载贵金属Au作为助催化剂,用于光催化CO_(2)和H2O反应,考察MgO含量和不同贵金属助催化剂对光催化活性的影响.发现Au和3%MgO共改性的g-C_(3)N_(4)光催化剂上表现出最佳的光催化性能,3 h后CO,CH_(4),CH3OH和CH3CHO的产量分别高达423.9、83.2、47.2和130.4μmol/g.本文分别研究了MgO和贵金属Au作为助催化剂对光催化行为的影响.XPS结果表明,Au/MgO-g-C_(3)N_(4)纳米片中形成了Mg–N键;UV-vis漫反射光谱表明Au/MgO-g-C_(3)N_(4)复合催化剂能够大大地增强紫外和可见光的吸收,且Au纳米颗粒具有表示等离子体共振(SPR)效应;PL光谱、TRPL光谱和光电化学测试都显示了MgO和Au的加入可以有效地提高光生电荷载流子的分离效率,这是由于Mg–N键的存在以及Au纳米颗粒对电子的捕获作用.CO_(2)吸附曲线证明了MgO的存在能够增强对CO_(2)的吸附;CO_(2)-TPD测试则表明CO_(2)的有效吸附主要发生在MgO和Au纳米颗粒的界面处,而该界面正是光生电子�
基金
国家重点研究发展计划(2018YFB1502000)
英国皇家学会牛顿高级学者基金(NA191163),国家自然科学基金(21576050,51602052,51672210)
江苏省自然科学基金(BK20150604)
中央高校基本科研业务费专项资金资助(3207045403,3207045409,3207046414)
江苏省生物质与材料重点实验室基金(JSBEM202001)
江苏省高校优势学科建设工程资助项目(PAPD)
东南大学仲英青年学者.
