Enhanced photocatalytic H₂evolution over noble-metal-free NiS cocatalyst modified CdS nanorods/g-C₃N₄heterojunctions

Abstract

In this report, the CdS nanorods/g-C 3 N 4 heterojunctions loaded by noble-metal-free NiS cocatalyst were firstly fabricated by in situ hydrothermal method. The as-synthesized heterostructured photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution 10 transmission electron microscopy, UV-visible spectroscopy, nitrogen absorption, photoluminescence (PL) spectra, transient photocurrent responses and electrochemical impedance spectroscopy (EIS) measurements. Their photocatalytic activity for hydrogen production was evaluated using an aqueous solution containing triethanolamine under visible light (λ≥ 420 nm). The results clearly demonstrated that the ternary hybridization of NiS cocatalyst, 1D CdS nanorods and 2D g-C 3 N 4 nanosheets is a 15 promising strategy to achieve highly efficient visible-light-driven photocatalytic H 2 evolution. Among all the photocatalysts employed, the ternary hybrid g-C 3 N 4 -CdS-9%NiS composite materials show the best photocatalytic performance with a H 2 -production rate of 2563 umol h -1 g -1 , which is 1582 times higherthan that of the pristine g-C 3 N 4 . The enhanced photocatalytic activity was ascribed to the combined effects of NiS cocatalyst loading and the formation of the intimate nanoheterojunctions between 1D CdS nanorods 20 and 2D g-C 3 N 4 nanosheets, which was favorable for promoting charge transfer, improving separation efficiency of photoinduced electron-hole pairs from bulk to interfaces and accelerating the surface H 2evolutioth kinetics. This work would not only provide a promising photocatalyst candidate for applications in visible-light H 2 generation, but also offer a new insight into the construction of highly efficient and stable g-C 3 N 4 -based hybrid semiconductor nanocomposites for diverse photocatalytic 25 applications.

A review on g-C3N4 for photocatalytic water splitting and CO2 reduction

“…Note that this value can compare with the 1.0 wt% Pt loaded g-C 3 N 4 for H 2 generation (8.2 mol h -1 ) under otherwise same conditions [57]. In addition, nickel and cobalt compounds, such as cobaloxime [109], NiS [110,111] and NiS 2 [112] have also been demonstrated as co-catalysts to improve the H 2 evolution of g-C 3 N 4 under visible light irradiation. These works show the great potential of utilizing low cost transitional metal compounds as co-catalyst to substitute the noble metals in boosting the photocatalytic H 2 production of g-C 3 N 4 .…”

Reduced Oxygenated g‐C3N4 with Abundant Nitrogen Vacancies for Visible‐Light Photocatalytic Applications

“…The enhanced current signals show that the catalysts have higher electron‐transfer efficiencies. In addition, electrochemical impedance spectroscopy showed that RCNO has the lowest resistance (see the Supporting Information, Figure S8), which further confirmed the enhanced charge transfer rate.…”

g‐C3N4‐Based Heterostructured Photocatalysts

“…Bimetallic cocatalysts such as PtCo, [205] PdAu, [239] PtOAu [240] have exhibited higher H 2 photocatalytic activity than single noble metals. So far, numerous nonnoble metal cocatalysts have proven efficient in enhancing the photo catalytic H 2 generation activity of gC 3 N 4 , including FeO x , [228] MoS 2 , [229,[241][242][243][244] WS 2 , [245] NiS, [246][247][248] Ni 12 P 5 , [249] carbon nanotube (CNT), [232] carbon black, [233] carbon nanofiber, [222] Co(OH) 2 , [250] Ni(OH) 2 , [251,252] Cu(OH) 2 , [253] Ni(dmgH) 2, [254] and Ni [208,255,256] (Table 3). So far, numerous nonnoble metal cocatalysts have proven efficient in enhancing the photo catalytic H 2 generation activity of gC 3 N 4 , including FeO x , [228] MoS 2 , [229,[241][242][243][244] WS 2 , [245] NiS, [246][247][248] Ni 12 P 5 , [249] carbon nanotube (CNT), [232] carbon black, [233] carbon nanofiber, [222] Co(OH) 2 , [250] Ni(OH) 2 , [251,…”