• Pristine CaTiO 3 has no activity for SCR deNO x , while Ce-Fe-Mn doped could achieve almost 100% NO conversion at 135°C (GHSV = 72000 h -1 ). By selectively activating gaseous molecules, Ti, Fe, and Mn present apparent synergistic effects on accelerating the catalytic cycle of standard SCR. The photocarriers intensify oxidation rather than NH -to-NH 2 transformation. Although photocatalysis e...