研究目的
Investigating the mechanism of PdCrOx multi-component cocatalyst formation on SrTiO3 and its photocatalytic activity for overall water splitting.
研究成果
The Pd species in PdCrOx changes from oxide to a mixed oxide/metal phase with increased photoirradiation time, enhancing overall water-splitting activity by suppressing O2 photoreduction, a key backward reaction. Longer irradiation times optimize cocatalyst performance without significantly affecting H2 evolution from methanol solution.
研究不足
The study notes compositional inhomogeneity in deposited nanoparticles, making precise control difficult. The location of oxidized Pd species could not be detected in TEM images. The mechanistic details of Pd-Cr interaction enhancing H2 evolution are still under investigation.
1：Experimental Design and Method Selection:
The study used a photodeposition method under UV light irradiation (λ > 300 nm) for synthesizing PdCrOx/SrTiO3 samples, with characterization via TEM, XAFS (including EXAFS and XANES), and XPS to analyze structure and valence states. Photocatalytic reactions were conducted to assess water-splitting activity.
2：Sample Selection and Data Sources:
SrTiO3 was prepared using the polymerized complex method. PdCrOx cocatalyst was deposited on SrTiO3 using precursors Na2PdCl4·3H2O and K2CrO4 in a 10 vol% methanol aqueous solution.
3：List of Experimental Equipment and Materials:
Equipment included a 300 W xenon lamp for irradiation, gas chromatography (GC-3200 with TCD and MS-5A column) for gas analysis, TEM (JEM-2010F), XAFS at AR-NW10A and BL-9A beamlines, XPS (ESCA 3400), and UV-visible absorption spectroscopy. Materials included SrTiO3, Na2PdCl4·3H2O, K2CrO4, methanol, EDTA·2Na, and reference samples like Pd foil and PdO.
4：Experimental Procedures and Operational Workflow:
Samples were synthesized by irradiating the precursor solution for 0-5 h, with gases analyzed during deposition. Post-synthesis, samples were characterized using TEM, XAFS, and XPS. Photocatalytic reactions involved dispersing catalyst in water or methanol solution under irradiation, with gas evolution monitored. Backward reactions were studied under dark or irradiated conditions with added gases.
5：Data Analysis Methods:
XAFS data were analyzed using Athena and Artemis programs. XPS data were referenced to C 1s peak. Gas evolution rates were quantified via gas chromatography, and Cr deposition was measured using UV-visible absorption spectroscopy.
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