Fe-Ni bimetallic adsorbent for efficient As2O3 removal from coal-fired flue gas under a wide temperature range: Experimental and DFT study

•A novel Fe-Ni bimetallic adsorbent is prepared by hydrothermal calcination.•Fe-Ni bimetallic adsorbent exhibits outstanding arsenic adsorption performance and anti-sintering ability under wide temperature range (500–900 °C).•DFT reveals the microscopic mechanism improving the oxidation performance of Fe-Ni adsorbent.•The synergistic effect of Ni and O promotes the capture of As2O3.