Bridging and bonding: Zinc and potassium co-assisted crystalline g-C3N4 for significant highly efficient upon photocatalytic hydrogen evolution

Abstract Cation-assisted method typifies a common means of improving photocatalysis efficiency. However, it is difficult to create a superior breakthrough in hydrogen evolution recently. In this work, we exhibit dramatically enhanced lighting harvest in a Zn2+ and K+ synergetic modulating g-C3N4 crystal, due to that its absorption edge is tuned from 460 nm for g-C3N4 to visible-light region (582 nm), as well as the bandgap is reduced to 2.13 eV. The density functional theory (DFT) calculations reveal that K+ ions construct the “ion-bridge” between perpendicular interlayers, and Zn2+ ions prefer to occupy the vacancy of π-π conjugate planes of the tri-s-triazine, creating the “bonding” between hybridized sp2 orbitals. “Bridging and Bonding” jointly endow this as-prepared material a gorgeous lattice fringe, a stable structure and a superior photocatalytic activity. The efficient hydrogen evolution of the modified g-C3N4 co-doped with Zn2+ and K+ reveals is about 45.5 times of that of pristine g-C3N4, and the apparent quantum yield (AQY) is about of 0.52% at 540 nm, which is 8.7 times higher than that of g-C3N4. It is anticipated that this work will break the deadlock in hydrogen evolution photocatalysis and broaden novel horizons on the g-C3N4-based application.