一维/二维W_(18)O_(49)/多孔g-C_(3)N_(4)梯形异质结构建及其光催化析氢性能研究

Construction of 1D/2D W_(18)O_(49)/Porous g-C_(3)N_(4) S-Scheme Heterojunction with Enhanced Photocatalytic H2 Evolution

提高光催化分解水制氢的效率是能量转换领域的关键挑战。本研究首先合成了二维多孔氮化碳(PCN),然后在二维PCN上原位生长了一维W_(18)O_(49)(WO),形成了一种新型的梯形(S型)异质结。该异质结可以加快界面电荷的分离和转移,赋予WO/PCN体系更好的氧化还原能力。此外,具有多孔结构的PCN提供了更多的催化活性位点。与WO和PCN相比,20%WO/PCN复合材料具有更高的H_(2)产率(1700μmol∙g^(−1)∙h^(−1)),是PCN(30μmol∙g^(−1)∙h^(−1))的56倍。本研究提供了一种新S型光催化剂用于光催化制氢领域。

Photocatalytic hydrogen production is an effective strategy for addressing energy shortage and converting solar energy into chemical energy.Exploring effective strategies to improve photocatalytic H_(2) production is a key challenge in the field of energy conversion.There are numerous oxygen vacancies on the surface of non-stoichiometric W_(18)O_(49)(WO),which result in suitable light absorption performance,but the hydrogen evolution effect is not ideal because the band potential does not reach the hydrogen evolution potential.A suitable heterojunction is constructed to optimize defects such as high carrier recombination rate and low photocatalytic performance in a semiconductor.Herein,2D porous carbon nitride(PCN)is synthesized,followed by the in situ growth of 1D WO on the PCN to realize a step-scheme(S-scheme)heterojunction.When WO and PCN are composited,the difference between the Fermi levels of WO and PCN leads to electron migration,which balances the Fermi levels of WO and PCN.Electron transfer leads to the formation of an interfacial electric field and bends the energy bands of WO and PCN,thereby resulting in the recombination of unused electrons and holes while leaving used electrons and holes,which can accelerate the separation and charge transfer at the interface and endow the WO/PCN system with better redox capabilities.In addition,PCN with a porous structure provides more catalytic active sites.The photocatalytic performance of the sample can be investigated using the amount of hydrogen released.Compared to WO and PCN,20%WO/PCN composite has a higher H_(2) production rate(1700μmol∙g^(−1)∙h^(−1)),which is 56 times greater than that of PCN(30μmol∙g^(−1)∙h^(−1)).This study shows the possibility of the application of S-scheme heterojunction in the field of photocatalytic H_(2) production.