In Situ Bond Modulation of Graphitic Carbon Nitride to Construct p-n Homojunctions for Enhanced Photocatalytic Hydrogen Production
In Situ Bond Modulation of Graphitic Carbon Nitride to Construct p-n Homojunctions for Enhanced Photocatalytic Hydrogen Production
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DOI：
10.1002/adfm.201602779
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发表时间：
2016-10-04
影响因子：
19
通讯作者：
Ye, Jinhua
中科院分区：
文献类型：
--
作者：
Liu, Guigao;Zhao, Guixia;Ye, Jinhua
石墨氮化碳（g-C3N4）最近已成为一种有吸引力的太阳能转换光催化剂。然而，由于太阳光吸收不足和电子空穴复合速度快，g-C3N4 的光催化活性仍然中等。在此，报道了缺陷修饰的 g-C3N4 (DCN) 光催化剂，该催化剂在温和条件下易于制备，并且显示出更大的光吸收范围，带隙从 2.75 eV 降低至 2.00 eV。更重要的是，氰基末端CN基团作为电子受体被引入DCN片边缘，赋予DCN同时具有n型和p型导电性，从而产生p-n同质结。这种同质结结构被证明在电荷转移和分离方面非常有效，并使光催化 H-2 析出活性提高了五倍。这些发现加深了对 g-C3N4 基材料缺陷相关问题的理解。此外，通过缺陷诱导的自功能化构建同质结结构的能力为实现 g-C3N4 和相关聚合物半导体的精确能带工程提供了一种有前景的策略，以实现更高效的太阳能转换应用。
Graphitic carbon nitride (g-C3N4) has recently emerged as an attractive photocatalyst for solar energy conversion. However, the photocatalytic activities of g-C3N4 remain moderate because of the insufficient solar-light absorption and the fast electron-hole recombination. Here, defect-modified g-C3N4 (DCN) photocatalysts, which are easily prepared under mild conditions and show much extended light absorption with band gaps decreased from 2.75 to 2.00 eV, are reported. More importantly, cyano terminal C N groups, acting as electron acceptors, are introduced into the DCN sheet edge, which endows the DCN with both n- and p-type conductivities, consequently giving rise to the generation of p-n homojunctions. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation, and results in a fivefold enhanced photocatalytic H-2 evolution activity. The findings deepen the understanding on the defect-related issues of g-C3N4-based materials. Additionally, the ability to build homojunction structures by the defect-induced self-functionalization presents a promising strategy to realize precise band engineering of g-C3N4 and related polymer semiconductors for more efficient solar energy conversion applications.