Water pollution is one of the most important problems in the field of environmental protection in the whole world, and organic pollution is a critical one for wastewater pollution problems. How to solve the problem effectively has triggered a common concern in the area of environmental protection nowadays. Around this problem, scientists have carried out a lot of research; due to the advantages of high efficiency, a lack of secondary pollution, and low cost, photocatalytic technology has attracted more and more attention. In the past, MnO₂ was seldom used in the field of water pollution treatment due to its easy agglomeration and low catalytic activity at low temperatures. With the development of carbon materials, it was found that the composite of carbon materials and MnO₂ could overcome the above defects, and the composite had good photocatalytic performance, and the research on the photocatalytic performance of MnO₂-carbon materials has gradually become a research hotspot in recent years. This review covers recent progress on MnO₂-carbon materials for photocatalytic water treatment. We focus on the preparation methods of MnO₂ and different kinds of carbon material composites and the application of composite materials in the removal of phenolic compounds, antibiotics, organic dyes, and heavy metal ions in water. Finally, we present our perspective on the challenges and future research directions of MnO₂-carbon materials in the field of environmental applications.

Moisture is a ubiquitous and clean resource in nature, which continuously diffuses in the atmosphere and demonstrates huge chemical potential energy that is difficult to be utilized. Recently, the generation of power from interactions between graphene and gaseous water molecules in moisture has triggered great research interest that could provide a novel energy conversion system for our society. graphene-based assemblies have been considered as ideal platforms for moist-electric generation (MEG) in many studies, because of the abundant of functional groups, controllable microstructure and diverse macro morphologies. Therefore, in this short review, we will first state the preparation techniques of graphene-based assemblies for MEG. Then, the fundamental mechanisms of MEG are discussed and the latest advances on graphene MEG are reviewed. Finally, an overview of the current challenges and future development trends in graphene MEG is provided.