In situ derived Ni2P/Ni encapsulated in carbon/g-C3N4 hybrids from metal-organic frameworks/g-C3N4 for efficient photocatalytic hydrogen evolution

Tightly coupling multiple cocatalysts into semiconductors for efficient charge separation is a promising way to enhance photocatalytic H-2 production. In this work, Ni2P/Ni nanoparticles (NPs) encapsulated in carbon/g-C3N4 hybrids derived from in situ pyrolysis and phosphidation of Ni-based metal-organic frameworks/g-C3N4 (NiMOF/g-C3N4) precursor were used as photocatalysts for H-2-evolution under visible-light irradiation. The highest H-2-evolution rate over optimized Ni2P/Ni@C/g-C3N4-550 was 18.04 mmol g(-1) h(-1) with 1.0 mmol L-1 of Eosin Y (EY)-sensitization (compared to 0.21 mmol g(-1) h(-1) without EY-sensitization), 13 times higher than that of pristine g-C3N4 (1.33 mmol g(-1) h(-1)). The apparent quantum efficiency at 420 nm was 58.1%. This enhanced photocatalytic activity can be attributed to an efficient and rapid separation of the photo-generated charges from excited EY and g-C3N4 to Ni2P/Ni with carbon as an electron transport bridge, intimate contact of each components, staggered band alignment among g-C3N4, Ni and Ni2P, as well as accelerated proton reduction reaction by Ni2P/Ni NPs. This work provides new insights into the construction of MOFs-derived cocatalyst for photocatalytic H-2 production.