Superior synergy of g-C3N4/Cd compounds and Al-MOF-derived nanoporous carbon for photocatalytic hydrogen evolution

[Display omitted] •Synergy of g-C3N4/Cd(OH)2/CdS /nanoporous carbon in photocatalytic H2 evolution.•Narrowed Eg caused by g-C3N4 modification with Cd compounds and nanoporous carbon.•Reduction of overpotential of H+ reduction after g-C3N4 modification.•Cd(OH)2/CdS and nanoporous carbon acted as electron acceptors.•60-fold enhancement of hydrogen evolution rate over four-component photocatalyst. Graphitic carbon nitride (gCN) exhibits outstanding photocatalytic performances toward H2 evolution. However, it can be further improved by overcoming its disadvantages such fast recombination of pohotogenerated electron-hole pairs. Here, we propose an efficient photocatalysts based on three components: (i) gCN modified with (ii) cadmium compounds (CdX: Cd(OH)2, CdS, CdO) and (iii) nanoporous carbon flakes (NPC) derived from Al-metal organic framework. The fabrication method was focused on finding the optimal hybrid composition dispalying the most powerful performance. Three main aspects were revealed: (i) band gap of gCN narrowing from 2.70 eV to 2.32 eV, (ii) reduction of overpotential for H2 evolution, as conduction band minimum (CBM) moved from −1.07 V vs. NHE to −0.63 V vs. NHE and (iii) enhanced charge separation, since CdX and NPC acted as electron acceptors. These factors had an effect on ˜60-fold enhancement of the photocatalytic efficiency. The mechanism of the photocatalytic process was discussed.