“…A series of metal oxide supports, including MnO x , TiO 2 , CeO 2 , and FeO x and their composites, such as MnO x -CeO 2 , CeO 2 -Co 3 O 4 , and In 2 O 3 -SnO 2 , have been used in a wide range of studies on catalytic HCHO due to their excellent redox effects, the high dispersity of the supported metal oxides, and the metal-support interactions (MSIs) between the supports and the supported metal oxides [9][10][11]. However, applications of these common metal oxide supports are restricted owing to certain disadvantages, such as irregular shapes, unsuitable sizes, uneven structures, and high prices [12,13]. Against this backdrop, despite their own problems, biochar supports hold potential for HCHO removal because of their low prices, adjustable sizes, large specific surface areas, excellent hydrophobicity, and rich sources [14].…”