研究目的
To investigate the one-step hydrogen and oxygen evolution through a photocatalytic membrane reactor using suspended nanosized Au/TiO2 and Au/CeO2 photocatalysts, a modified Nafion membrane, and Fe3+/Fe2+ as a redox mediator under visible light irradiation.
研究成果
The research successfully demonstrated simultaneous hydrogen and oxygen evolution using a Z-scheme photocatalytic membrane reactor with Au/TiO2 and Au/CeO2 under visible light. Optimal conditions included 5 mM Fe3+ concentration and 0.25 wt% gold loading, producing stoichiometric amounts of gases. The Nafion membrane and Fe3+/Fe2+ redox couple were crucial for system performance, but ion permeation rates limited long-term efficiency. This approach shows promise for renewable energy applications but requires improvements in membrane design and mediator stability.
研究不足
The study is limited by the use of a specific membrane (Nafion 117) and redox mediator (Fe3+/Fe2+), which may not be optimal for all conditions. The photocatalytic activity is constrained by the permeation rate of iron ions through the membrane, leading to reduced efficiency over time. The experiments were conducted under laboratory conditions with controlled parameters, and scalability to industrial applications may require further optimization.
1：Experimental Design and Method Selection:
The study employed a Z-scheme mechanism for overall water splitting, using a two-compartment photocatalytic membrane reactor separated by a Nafion membrane to allow electron transfer via Fe3+/Fe2+ redox couple.
2：Sample Selection and Data Sources:
Commercial TiO2 P25 (Degussa) and synthesized CeO2 via alginate templating were used; gold nanoparticles were deposited via deposition-precipitation.
3：List of Experimental Equipment and Materials:
Equipment included a two-compartment Pyrex cell, 125-W medium-pressure mercury lamp (DLU, HDLM E27), gas chromatograph (Agilent 7890A), TEM microscope (Jeol 200 Cx), spectrophotometer for iron determination. Materials included Nafion 117 membrane (Aldrich), Fe2(SO4)3, AuHCl4, Milli-Q water.
4：Experimental Procedures and Operational Workflow:
The membrane was modified by boiling in HNO3, conditioning in NaOH and H2SO4, and immersing in Fe2(SO4)
5：Photocatalytic tests involved irradiating suspensions in each compartment, purging with argon, and measuring gas evolution via GC. Diffusion tests were conducted to study iron ion transport. Data Analysis Methods:
Gas evolution was quantified using GC with thermal conductivity detector; iron concentrations were determined spectrophotometrically; TEM was used for particle size analysis.
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