Heterostructure α-Fe2O3(0 0 1)/g-C3N4(0 0 2) adsorbent to remove As2O3 in simulated coal flue gas: Experimental and DFT study

•The α-Fe2O3/g-C3N4 composite with a heterostructure was prepared, which compensates for the insufficient surface area of conventional α-Fe2O3.•Through the TEM observation of the lattice spacing, the error between the theory and the experimental results is only about 2%.•The oxidation mechanism of As(III) is deduced, and the removal of As2O3 by α-Fe2O3/g-C3N4 can be understood as adsorption before catalysis.