▎ 摘　　要

Air pollution has a considerable impact on human beings among environmental problems. In particular, particulate matter less than 2.5 micrometers in diameter (PM2.5) is the biggest problem that threatens human health. In this work, we present a filter that removes PM2.5 at high efficiency with a low pressure-drop. A high surface area afforded by a two-dimensional nanomaterial of reduced graphene oxide (rGO) and a highly porous structure provided by rGO foam render the filter efficient and enable low pressure drop operation. The filter with the rGO foam formed on both sides of a copper mesh plays the role of removing the outdoor PM and at the same time purifying the indoor PM efficiently. Repeated regeneration and reuse with little loss of efficiency demonstrates the robustness of the filter. Additionally, its quality factor which represents overall efficiency was almost twice the best ever reported in the literature. With advantages such as simple fabrication, easy scaling-up, bidirectionality, and low power consumption, the filter presented here would exemplify the desirable set of characteristics for PM removal filters.