研究目的
To develop an efficient and stable photocatalyst for hydrogen production from water reduction using solar energy, specifically by employing ternary nickel cobalt oxide (NiCo2O4) decorated on graphitic carbon nitride (g-C3N4) to enhance photocatalytic activity.
研究成果
The NiCo2O4/g-C3N4 composite exhibits significantly enhanced photocatalytic hydrogen production due to improved charge separation, higher surface area, and the presence of multivalent ions. The Z-scheme mechanism facilitates efficient carrier transfer, leading to a high H2 evolution rate of 5480 μmol·h-1·g-1 and good stability. This work provides insights for developing efficient photocatalysts using bimetallic oxides.
研究不足
The study may have limitations in scalability for industrial applications, potential variability in nanoparticle dispersion, and the use of sacrificial agents like TEOA, which may not be sustainable. Optimization of NiCo2O4 content is needed to avoid shielding effects, and further studies on long-term stability under real-world conditions are required.
1：Experimental Design and Method Selection:
The study involves synthesizing NiCo2O4/g-C3N4 composites via a reflux and calcination method to enhance photocatalytic hydrogen evolution. Theoretical models include Z-scheme charge transfer for improved carrier separation.
2：Sample Selection and Data Sources:
Samples include pristine g-C3N4, NiCo2O4, and composites with varying mass fractions of NiCo2O4 (e.g.,
3：5wt%-NiCo2O4/CN), prepared using urea, Co(NO3)2, Ni(NO3)2, and (NH4)2COData on photocatalytic performance and material properties are collected through experiments. List of Experimental Equipment and Materials:
Equipment includes a microwave muffle furnace (CEM PHOENIX), three-necked flask for reflux, X-ray diffraction (XRD) for phase analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption for BET surface area, UV-visible absorption spectroscopy, photoluminescence (PL) spectroscopy, photoelectrochemical measurements (I-t curves, EIS, LSV), and ultraviolet photoelectron spectroscopy (UPS). Materials include urea, Co(NO3)2, Ni(NO3)2, (NH4)2CO3, triethanolamine (TEOA) as sacrificial reagent, and rhodamine B (RhB) for trapping experiments.
4：Experimental Procedures and Operational Workflow:
g-C3N4 is synthesized by calcining urea at 550°C for 2 hours, then exfoliated by sonication. NiCo2O4/g-C3N4 composites are prepared by adding Co(NO3)2 and Ni(NO3)2 solutions to g-C3N4 suspension, adding (NH4)2CO3, refluxing at 100°C for 1 hour, washing, drying, and calcining at 300°C for
5：5 hours. Photocatalytic H2 evolution tests are conducted under simulated sunlight irradiation with TEOA. Material characterizations involve XRD, FT-IR, SEM, TEM, EDS, XPS, BET, UV-vis, PL, and electrochemical measurements. Trapping experiments use IPA, TEOA, and N2 to identify active species. Data Analysis Methods:
Data are analyzed using software for XRD pattern matching (JCPDS standards), XPS peak deconvolution, BET surface area calculation, Kubelka-Munk transformation for band gap determination, and statistical analysis of photocatalytic rates and electrochemical parameters.
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