Synergistic effect of isolated Co and Fe dual active sites boosting the photocatalytic hydrogen evolution reaction

Abstract The photocatalytic hydrogen evolution reaction is a promising and powerful approach to replace traditional fossil fuels. Herein, we have fabricated Fe, Co dual single atoms dispersed on nitrogen-doped graphene ((Fex, Coy)-NG) by freeze-drying method, which can as a highly efficient co-catalyst. The (Fex, Coy)-NG loaded mesoporous graphitic carbon nitride (mpg-C3N4) exhibits an excellently high performance for photocatalytic hydrogen evolution. The high activity can belong to two ways: (i) the ultrathin mpg-C3N4 not only increases the absorption and active sites but also shortens the charge migration distance; (ii) The nitrogen functional groups from NG can provide abundant coordination sites to evenly bind Fe and Co atoms. The photocatalytic hydrogen evolution performances (Fex, Coy)-NG co-catalyst with different content ratios of Fe atoms and Co atoms were also investigated. The optimized hydrogen production rate (1958 μmol·g-1) of 5 wt % (Fe0.2, Co0.8)-NG/mpg-C3N4 is obviously higher compared to the monometallic counterparts (5 wt % Fe-NG/mpg-C3N4 or 5 wt % Co-NG/mpg-C3N4). The higher photoactivities are due to the synergistic effect between Fe and Co.