Metal-Free 2D/2D Heterojunction of Graphitic Carbon Nitride/Graphdiyne for Improving the Hole Mobility of Graphitic Carbon Nitride

The design and synthesis of efficient metal-free photoelectrocatalysts for water splitting are of great significance, as nonmetal elements are generally earth abundant and environment friendly. As a typical metal-free semiconductor, g-C3N4 has received much attention in the field of photocatalytic water splitting. However, the poor photoinduced hole mobility of g-C3N4 restrains its catalytic performance. Herein, for the first time, graphdiyne (GDY) is used to interact with g-C3N4 to construct a metal-free 2D/2D heterojunction of g-C3N4/GDY as an efficient photoelectrocatalyst for water splitting. The g-C3N4/GDY photocathode exhibits enhanced photocarriers separation due to excellent hole transfer nature of graphdiyne and the structure of 2D/2D heterojunction of g-C3N4/GDY, realizing a sevenfold increase in electron life time (610 mu s) compared to that of g-C3N4 (88 mu s), and a threefold increase in photocurrent density (-98 mu A cm(-2)) compared to that of g-C3N4 photocathode (-32 mu A cm(-2)) at a potential of 0 V versus normal hydrogen electrode (NHE) in neutral aqueous solution. The photoelectrocatalytic performance can be further improved by fabricating Pt@ g-C3N4/GDY, which displays an photocurrent of -133 mu A cm(-2) at a potential of 0 V versus NHE in neutral aqueous solution. This work provides a new strategy for the design of efficient metal-free photoelectrocatalysts for water splitting.