Wang Fengzhi, Zhou Yusong, Pan Xinhua, Lu Bin, Huang Jingyun, Ye Zhizhen
State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
Phys Chem Chem Phys. 2018 Mar 7;20(10):6959-6969. doi: 10.1039/c7cp06909j.
A series of ZnO nanorod (NR)-reduced graphene oxide (rGO) nanocomposites (NCs) (i.e., ZnO-rGO NCs) with varying rGO loadings were fabricated by electrostatic self-assembly of positively charged ZnO NRs with negatively charged graphene oxide (GO), followed by the hydrothermal reduction of GO to rGO. When compared with bare ZnO NRs, ZnO-5% rGO exhibited significant photoactivity 6 times higher in the photodegradation of rhodamine B (RhB), and 2 times higher than ZnO-5% rGO(H) synthesized by hard integration of GO and ZnO NRs. In the same manner, ZnO-5% rGO exhibited a significant photoactivity 3 times higher in photodegrading phenol, which is 2 times higher than ZnO-5% rGO(H). Furthermore, the adsorption properties of ZnO-rGO NCs towards RhB and phenol were significantly different as a result of the opposite charges of the two pollutants in aqueous solution, which also led to the formation of different key free radicals during the degradation reaction. Based on various characterization techniques, it is concluded that the enhanced photoactivity and photostability of ZnO-5% rGO originated from the synergistic effects between ZnO NRs and rGO nanosheets including higher specific surface area, enhanced photogenerated carrier separation, and strengthened protection effects from intimate rGO coupling. However, these synergistic effects were weaker in ZnO-5% rGO(H) which reflects the key importance of surface charge modification in producing a well-contacted interface.
通过带正电荷的ZnO纳米棒与带负电荷的氧化石墨烯（GO）进行静电自组装，随后将GO水热还原为还原氧化石墨烯（rGO），制备了一系列具有不同rGO负载量的ZnO纳米棒（NR）-还原氧化石墨烯（rGO）纳米复合材料（NCs）（即ZnO-rGO NCs）。与裸露的ZnO纳米棒相比，ZnO-5% rGO在罗丹明B（RhB）的光降解中表现出显著的光活性，比裸露的ZnO纳米棒高6倍，比通过GO与ZnO纳米棒硬整合合成的ZnO-5% rGO（H）高2倍。同样，ZnO-5% rGO在苯酚光降解中的光活性显著提高，是ZnO-5% rGO（H）的3倍，比ZnO-5% rGO（H）高2倍。此外，由于两种污染物在水溶液中电荷相反，ZnO-rGO NCs对RhB和苯酚的吸附性能存在显著差异，这也导致了降解反应过程中形成不同的关键自由基。基于各种表征技术，得出结论：ZnO-5% rGO光活性和光稳定性的增强源于ZnO纳米棒与rGO纳米片之间的协同效应，包括更高的比表面积、增强的光生载流子分离以及rGO紧密耦合带来的强化保护作用。然而，这些协同效应在ZnO-5% rGO（H）中较弱，这反映了表面电荷修饰在产生良好接触界面方面的关键重要性。
