Energy-efficient catalytic removal of formaldehyde enabled by precisely Joule-heated Ag/Co3O4@mesoporous-carbon monoliths

The high-efficiency catalysts for the oxidative removal of volatile organic compounds (VOCs) as air pollutants are in urgent need. Because of the extremely low concentration of VOCs, very high intrinsic activity at low temperatures is required for the catalyst or the temperature has to be elevated, which causes unaffordable energy consumption. Here, a mesoporous three-dimensional-carbon-monolith (3DCM) supported Ag-Co3O4 bimetallic catalyst is fabricated for the catalytic removal of formaldehyde. Enabled by the excellent Joule-heating property of 3DCM, the catalyst can be precisely heated without the need to heat the largely excessive air and surroundings. By this means, the energy consumption of the whole device can be drastically reduced by 87%. As a proof-of-concept demonstration, in the presence of constant emission, the formaldehyde concentration can be reduced from 4 ppm to 600 ppb after 10 h reaction in a 2 m3 gastight chamber. The strategy here suggests a promising technology to eliminate VOCs efficiently, fast-responsively and energy-savingly.