**Jianlong Ge, Yifan Zhang, Young-Jung Heo and Soo-Jin Park \***

Department of Chemistry and Chemical Engineering, Inha University, 100 Inharo, Incheon 22212, Korea; gejianlong1121@126.com (J.G.); zyf910626@inhaian.net (Y.Z.); heoyj1211@inhaian.net (Y.-J.H.) **\*** Correspondence: sjpark@inha.ac.kr; Tel.: +82-32-860-7234; Fax: +82-32-860-5604

Received: 29 December 2018; Accepted: 28 January 2019; Published: 30 January 2019

**Abstract:** Serious water pollution and the exhausting of fossil resources have become worldwide urgent issues yet to be solved. Solar energy driving photocatalysis processes based on semiconductor catalysts is considered to be the most promising technique for the remediation of wastewater. However, the relatively low photocatalytic efficiency remains a critical limitation for the practical use of the photocatalysts. To solve this problem, numerous strategies have been developed for the preparation of advanced photocatalysts. Particularly, incorporating a semiconductor with various functional components from atoms to individual semiconductors or metals to form a composite catalyst have become a facile approach for the design of high-efficiency catalysts. Herein, the recent progress in the development of novel photocatalysts for wastewater treatment via various methods in the sight of composite techniques are systematically discussed. Moreover, a brief summary of the current challenges and an outlook for the development of composite photocatalysts in the area of wastewater treatment are provided.

**Keywords:** Composite catalysts; photocatalysis; synergy effect; solar energy; wastewater remediation
