Department of Chemistry, Zhejiang Sci-Tech University, 928 Second Avenue, Xiasha Higher Education Zone, Hangzhou 310018, China.
Department of Chemistry, Zhejiang Sci-Tech University, 928 Second Avenue, Xiasha Higher Education Zone, Hangzhou 310018, China.
J Colloid Interface Sci. 2017 Dec 1;507:209-216. doi: 10.1016/j.jcis.2017.08.002. Epub 2017 Aug 2.
Semiconductor photocatalysis currently suffered three main problems, low solar energy utilization, high photo-generated charge recombination rate and the heavy metal ions release by the photo-corrosion. Herein, we developed a visible-light-driven homojunction photocatalyst with the metal-free two-dimensional (2D) graphitic carbon nitride nanosheets (CNNS). By employing liquid exfoliation and chemical blowing approaches, we obtained two kinds of CNNS materials (le-CNNS and cb-CNNS) with different band structures, and subsequently fabricated the homojunction photocatalyst. This 2D/2D nanocomposited homojunction photocatalyst exhibited enhanced photocatalytic performance compared to these individual 2D nanosheets materials. Moreover, its well universality and reusability were also demonstrated by photo-degradation of various organic pollutants and five successive runs. By studying the optical properties and the electrochemical behavior, the band alignment of this homojunction was illustrated and the possible mechanism was proposed, where the transmitted electrons on the conduction band (CB) of le-CNNS would transport to the CB of cb-CNNS, and the holes on the valence band (VB) of cb-CNNS transferred to the VB of le-CNNS, therefore promoting the photo-induced carrier separation. Additionally, the photoluminescence, electrochemical impendence and photocurrent measurements further demonstrated that the recombination of photo-excited electron-hole pairs had been efficiently suppressed in the homojunction and were respectively collected on different CNNS components.
半导体光催化目前存在三个主要问题，即太阳能利用率低、光生载流子复合率高以及光腐蚀导致的重金属离子释放。在此，我们开发了一种具有无金属二维（2D）石墨相氮化碳纳米片（CNNS）的可见光驱动同质结光催化剂。通过采用液相剥离和化学吹气法，我们获得了两种具有不同能带结构的 CNNS 材料（le-CNNS 和 cb-CNNS），并随后制备了同质结光催化剂。与这些单独的 2D 纳米片材料相比，这种 2D/2D 纳米复合同质结光催化剂表现出增强的光催化性能。此外，通过光降解各种有机污染物和五次连续运行，还证明了其良好的通用性和可重复使用性。通过研究光学性质和电化学行为，说明了该同质结的能带排列，并提出了可能的机制，其中 le-CNNS 的导带（CB）上的传输电子将迁移到 cb-CNNS 的 CB，cb-CNNS 的价带（VB）上的空穴转移到 le-CNNS 的 VB，从而促进光致载流子分离。此外，光致发光、电化学阻抗和光电流测量进一步表明，在同质结中有效地抑制了光生电子-空穴对的复合，并且分别在不同的 CNNS 组件上收集。
