Graphitic C3N4 modified by Ni2P cocatalyst: An efficient, robust and low cost photocatalyst for visible-light-driven H2 evolution from water

- The H2 evolution rate of g-C3N4/Ni2P-0.48% is higher than that of g-C3N4/Pt-0.48%.
- The stable H2 evolution activity is observed for g-C3N4/Ni2P-0.48%.
- The g-C3N4/Ni2P-0.48% shows enhanced transfer of photo-induced charges.
- The synergistic effect between adjacent Ni and P facilitates fast H2 evolution.

The development of an efficient, robust and low cost catalyst for photocatalytic H2 evolution is an uphill challenge and has attracted plenty of researchers' interest. Herein, we report g-C3N4/Ni2P composite photocatalyst for H2 evolution reaction in which Ni2P acts as a noble-metal-free cocatalyst for g-C3N4. The g-C3N4/Ni2P is prepared based on two-step hydrothermal and phosphidation method. The optimum H2 evolution ability is obtained when the loaded weight percent of Ni2P is 0.48% (g-C3N4/Ni2P-0.48%), along with a corresponding H2 evolution rate of 5.67 μmol h−1. This value is about 1418 times more than pure g-C3N4 and obviously higher than that of Pt modified g-C3N4 (3.78 μmol h−1). In addition, the g-C3N4/Ni2P-0.48% catalyst demonstrates almost negligible photocatalytic degradation capability even after eight repeated cycles (a reaction time of 12 h per cycle). The introduction of Ni2P cocatalyst significantly accelerates the separation and transfer of photogenerated electrons of g-C3N4, hence resulting in enhanced H2 evolution efficiency. In addition, the Ni and P in Ni2P cocatalyst act as the hydride-acceptor and proton-acceptor centers, respectively, which synergistically facilitate the fast generation of H2.