Photocatalytic H2 generation via CoP quantum-dot-modified g-C3N4 synthesized by electroless plating

Photocatalytic water splitting is a promising method for hydrogen production. Numerous efficient photocatalysts have been synthesized and utilized. However, photocatalysts without a noble metal as the co-catalyst have been rarely reported. Herein, a CoP co-catalyst-modified graphitic-C3N4 (g-C3N4/CoP) is investigated for photocatalytic water splitting to produce H2. The g-C3N4/CoP composite is synthesized in two steps. The first step is related to thermal decomposition, and the second step involves an electroless plating technique. The photocatalytic activity for hydrogen evolution reactions of g-C3N4 is distinctly increased by loading the appropriate amount of CoP quantum dots (QDs). Among the as-synthesized samples, the optimized one (g-C3N4/CoP-4%) shows exceptional photocatalytic activity as compared with pristine g-C3N4, generating H2 at a rate of 936 μ mol g−1 h−1, even higher than that of g-C3N4 with 4 wt% Pt (665 μmol g−1 h−1). The UV-visible and optical absorption behavior confirms that g-C3N4 has an absorption edge at 451 nm, but after being composited with CoP, g-C3N4/CoP-4% has an absorption edge at 497 nm. Furthermore, photoluminescence and photocurrent measurements confirm that loading CoP QDs to pristine g-C3N4 not only enhances the charge separation, but also improves the transfer of photogenerated e−-h+ pairs, thus improving the photocatalytic performance of the catalyst to generate H2. This work demonstrates a feasible strategy for the synthesis of highly efficient metal phosphide-loaded g-C3N4 for hydrogen generation.