Pt(Cu) catalyst on TiO2 powder support prepared by photodeposition-galvanic replacement method

Methanol Oxidation at Platinum Coated Black Titania Nanotubes and Titanium Felt Electrodes

Optimized Pt-based methanol oxidation reaction (MOR) anodes are essential for commercial direct methanol fuel cells (DMFCs) and methanol electrolyzers for hydrogen production. High surface area Ti supports are known to increase Pt catalytic activity and utilization. Pt has been deposited on black titania nanotubes (bTNTs), Ti felts and, for comparison, Ti foils by a galvanic deposition process, whereby Pt(IV) from a chloroplatinate solution is spontaneously reduced to metallic Pt (at 65 °C) onto chemically reduced (by CaH2) TNTs (resulting in bTNTs), chemically etched (HCl + NaF) Ti felts and grinded Ti foils. All Pt/Ti-based electrodes prepared by this method showed enhanced intrinsic catalytic activity towards MOR when compared to Pt and other Pt/Ti-based catalysts. The very high/high mass specific activity of Pt/bTNTs (ca 700 mA mgPt−1 at the voltammetric peak of 5 mV s−1 in 0.5 M MeOH) and of Pt/Ti-felt (ca 60 mA mgPt−1, accordingly) make these electrodes good candidates for MOR anodes and/or reactive Gas Diffusion Layer Electrodes (GDLEs) in DMFCs and/or methanol electrolysis cells.

Enhanced Photocatalytic Degradation of Antibiotic and Hydrogen Production by Iron Doped Cerium(IV) Oxide

Norfloxacin (NF) is an emerging antibiotic contaminant due to its significant accumulation in the environment. Photocatalytic degradation is an effective method for removing emerging contaminant compounds in aqueous solution; however, it is not commonly applied because of the poor solubility of contaminant compounds in water. In this study, a photocatalytic degradation experiment was carried out on NF using a self-made ceria catalyst. At an initial concentration of NF of 2.5 mg L^-1, the dosage of CeO₂ was 0.1 g L^-1 photocatalyst in water, and the initial pH of the NF solution was 8.0. With a reaction time of 180 min, the total removal rate of NF could reach 95%. Additionally, the studies on hydrogen production show that the maximum hydrogen production with 2% Fe-CeO₂ can reach 25,670 μmol h^-1 g^-1 under close to 8 W of 365 nm, a methanol concentration of 20%, and a catalyst dose of 0.1 g L^-1 photocatalyst in water. Furthermore, the intensities of photoluminescence (PL) emission peaks decreased with increased Fe-doped amounts on CeO₂, suggesting that the irradiative recombination seemed to be weakened.

The Effect of Carbon Content on Methanol Oxidation and Photo-Oxidation at Pt-TiO2-C Electrodes

The oxidation of methanol is studied at TiO2-supported Pt electrodes of varied high surface area carbon content (in the 30-5% w/w range) and C÷Ti atom ratio (in the 3.0-0.4 ratio). The Pt-TiO2 catalyst is prepared by a photo-deposition process and C nanoparticles (Vulcan XC72R) are added by simple ultrasonic mixing. The optimum C÷Ti atom ratio of the prepared catalyst for methanol electro-oxidation is found to be 1.5, resulting from the interplay of C properties (increased electronic conductivity and methanol adsorption), those of TiO2 (synergistic effect on Pt and photo-activity), as well as the catalyst film thickness. The intrinsic catalytic activity of the best Pt-TiO2/C catalyst is better than that of a commercial Pt/C catalyst and could be further improved by nearly 25% upon UV illumination, whose periodic application can also limit current deterioration.

High performance of PtCu@TiO2 nanocatalysts toward methanol oxidation reaction: from synthesis to molecular picture insight

The electrocatalytic production of hydrogen from methanol dehydrogenation successfully uses platinum catalysts. However, they are expensive and Pt has the tendency to be poisoned from the intermediate compounds, formed during the methanol oxidation reaction (MOR). For these two reasons, there has been active research for alternative bi- and tri-component Pt-based catalysts. Herein, PtCu nanoparticles deposited on titania were studied and proposed to be efficient MOR catalysts. The catalyst was prepared by photo-deposition of Cu on a high-surface-area TiO₂ powder support, followed by a partial galvanic displacement of the Cu deposit by platinum. The morphology and structure of the catalyst were characterized by physicochemical methods. The PtCu@TiO₂ electro-catalyst has higher intrinsic catalytic activity and comparable mass specific activity for MOR in comparison with a commercial Pt/C catalyst. The experimental analyses were complemented by density functional theory-based computations. The theoretical results revealed that the most energetically favorable Pt and Cu arrangement in the supported PtCu nanoparticles was core (Cu)–shell (Pt) and/or phase-separated. The inter-atomic interactions responsible for the bimetallic cluster stabilization on titania were highlighted from the computed electronic charge distribution.

Computed adhesion energies of pure and bimetallic PtCu clusters (regular alloy, phase-separated, core–shell) on TiO₂ anatase support.