▎ 摘　　要

The COVID-19 pandemic that is still prevalent around the globe each day consumes massive disposable face masks and consequently lays a heavy burden on waste management. Meanwhile, the incineration of these medical wastes further escalates the already overwhelming carbon emission that leads to global warming and climate change. To offer a potential solution addressing medical waste and CO2 emission challenges, we herein develop a synthetic protocol to upgrade face masks into Ni, N-doped graphene (Ni-N-C) sheet catalysts for selectively reducing CO2 into CO electrochemically. The high specific surface area and the uniform dispersion of Ni active sites of the catalyst derived from a regular disposable face mask enable a near-unity CO Faradaic efficiency (FE) at the current density of 200 mA cm(-2). This study offers outside-of-the-box thinking to address environmental issues by turning medical wastes into CO2 reduction catalysts.