By first-principles calculations, M3B4-type (M=Cr, Mo, Mn, Ti, Zr, Hf, V, Nb, and Ta) MBenes show good catalytic activity for the conversion of CO2 to CH4, where the limiting potentials of Mo3B4 and Cr3B4 are −0.48 and −0.66 V. In addition, ΔG(*OCHO...