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Novel hybrids of graphitic carbon nitride sensitized with free-base meso-tetrakis(carboxyphenyl) porphyrins for efficient visible light photocatalytic hydrogen production
Applied Catalysis B: Environment and Energy ( IF 22.1 ) Pub Date : 2017-08-30 , DOI: 10.1016/j.apcatb.2017.08.079
Eliana S. Da Silva , Nuno M.M. Moura , M. Graça P.M.S. Neves , Ana Coutinho , Manuel Prieto , Cláudia G. Silva , Joaquim L. Faria

Novel hybrid photocatalysts of graphitic carbon nitride (g-C3N4, CN) sensitized with free-base porphyrins were prepared by impregnation through non-covalent interactions. Their photocatalytic activity was evaluated towards the generation of hydrogen (H2) from water splitting. For this purpose, and in order to ascertain the influence of the carboxy substituents groups and their position on the porphyrin periphery on H2 production, the porphyrins meso-tetraphenylporphyrin (TPP), meso-tetrakis(meta-carboxyphenyl)porphyrin (mTCPP) and meso-tetrakis(para-carboxyphenyl)porphyrin (pTCPP) were used. All the hybrids (TPP-CN, mTCPP-CN and pTCPP-CN) show higher performance for photocatalytic H2 production than that of pure CN. Among all the hybrids, mTCPP-CN presents the highest amount of H2 evolved, being of 326 and 48.4 μmol under 6 h of UV–vis and visible light (λ > 400 nm) irradiation, respectively. This photocatalyst was fully characterized by UV-vis, FTIR, XRD, XPS, SEM, TEM, N2 isotherms and steady-state and time-resolved fluorescence measurements. The fluorescence emission of the mTCPP porphyrin was remarkably quenched by CN semiconductor for the various hybrids mTCPP-CN containing different amounts of mTCPP, consistent with electron injection from the porphyrin excited state into the conduction band of the semiconductor. This works demonstrates that the sensitization of CN with dye porphyrins enhances the photocatalytic H2 evolution under UV–vis and visible light irradiation, making it a potential material for solar conversion to produce hydrogen from water.

中文翻译:

新型的用游离碱的内消旋-四(羧苯基)卟啉敏化的石墨氮化碳的杂化物,可有效地产生可见光光催化制氢

通过非共价相互作用浸渍,制备了用游离碱卟啉敏化的新型石墨碳氮化物杂化光催化剂(gC 3 N 4,CN)。对它们的光催化活性进行了评估,以了解水分解产生的氢(H 2)。为了这个目的,并以确定的羧基的取代基团的影响,而H上的卟啉周边它们的位置2的生产,卟啉的内消旋-tetraphenylporphyrin(TPP),内消旋-四(间位-carboxyphenyl)卟啉(TCPP)和介观的-tetrakis(para使用了-羧基苯基)卟啉(p TCPP)。所有杂种(TPP-CN,m TCPP-CN和p TCPP-CN)对光催化H 2的生产表现均高于纯CN。在所有杂种中,m TCPP-CN表现出最高的H 2释放量,在UV-vis和可见光(λ> 400 nm)照射6 h下分别为326和48.4μmol。通过紫外可见光谱,FTIR,XRD,XPS,SEM,TEM,N 2等温线以及稳态和时间分辨荧光测量对这种光催化剂进行了全面表征。CN半导体对各种杂种mm TCPP卟啉的荧光发射显着淬灭TCPP-CN包含不同数量的m TCPP,这与电子从卟啉激发态注入半导体的导带一致。这项工作表明,用染料卟啉敏化CN可以增强UV-vis和可见光照射下H 2的光催化释放,使其成为潜在的太阳能转化材料,以从水中产生氢气。
更新日期:2017-08-31
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