Research

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15 pages, 2863 KiB

Open AccessArticle

Mild Preoxidation Treatment of Pt/TiO₂ Catalyst and Its Enhanced Low Temperature Formaldehyde Decomposition

by Kangzhong Shi, Lei Wang, Long Li, Xuejuan Zhao, Yuanyuan Chen, Zelin Hua, Xiaobao Li, Xiaoli Gu and Licheng Li

Catalysts 2019, 9(8), 694; https://doi.org/10.3390/catal9080694 - 16 Aug 2019

Cited by 18 | Viewed by 3594

Abstract

The typical platinum nanoparticles loaded on titania (Pt/TiO₂) were pretreated with mild oxidation (<300 °C) in pure oxygen to enhance the low-temperature formaldehyde (HCHO) decomposition performance. The structural properties of support and platinum nanoparticles were characterized by X-ray diffraction (XRD), physical [...] Read more.

The typical platinum nanoparticles loaded on titania (Pt/TiO₂) were pretreated with mild oxidation (<300 °C) in pure oxygen to enhance the low-temperature formaldehyde (HCHO) decomposition performance. The structural properties of support and platinum nanoparticles were characterized by X-ray diffraction (XRD), physical adsorption/desorption, high-resolution transmission electron microscopy (HRTEM), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFITS), and temperature-programmed reduction and oxidation (TPR and TPO). The catalytic results showed that the low temperature HCHO decomposition activity of mild pre-oxidized Pt/TiO₂ was around three times that of the pristine one. According to the characterization results, the structure of the Pt/TiO₂ support and their Pt particle sizes had negligible change after pre-oxidation treatment. The cationic Pt content of Pt/TiO₂ and surface roughness of Pt nanoparticles gradually increased with the increasing temperature of the pre-oxidation treatment. Mild pre-oxidation treatment was beneficial to the oxygen activation and water dissociation of Pt/TiO₂. In situ HCHO-DFIRTS results showed that the mild pre-oxidation treatment could enhance the dehydrogenation of formate. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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16 pages, 7028 KiB

Open AccessArticle

Salt-Templated Platinum-Copper Porous Macrobeams for Ethanol Oxidation

by F. John Burpo, Enoch A. Nagelli, Anchor R. Losch, Jack K. Bui, Gregory T. Forcherio, David R. Baker, Joshua P. McClure, Stephen F. Bartolucci and Deryn D. Chu

Catalysts 2019, 9(8), 662; https://doi.org/10.3390/catal9080662 - 02 Aug 2019

Cited by 8 | Viewed by 3977

Abstract

Platinum nanomaterials provide an excellent catalytic activity for diverse applications and given its high cost, platinum alloys and bi-metallic nanomaterials with transition metals are appealing for low cost and catalytic specificity. Here the synthesis of hierarchically porous Pt–Cu macrobeams and macrotubes templated from [...] Read more.

Platinum nanomaterials provide an excellent catalytic activity for diverse applications and given its high cost, platinum alloys and bi-metallic nanomaterials with transition metals are appealing for low cost and catalytic specificity. Here the synthesis of hierarchically porous Pt–Cu macrobeams and macrotubes templated from Magnus’s salt derivative needles is demonstrated. The metal composition was controlled through the combination of [PtCl₄]²⁻ with [Pt(NH₃)₄]²⁺ and [Cu(NH₃)₄]²⁺ ions in different ratios to form salt needle templates. Polycrystalline Pt–Cu porous macrotubes and macrobeams 10’ s–100’ s μm long with square cross-sections were formed through chemical reduction with dimethylamine borane (DMAB) and NaBH₄, respectively. Specific capacitance as high as 20.7 F/g was demonstrated with cyclic voltammetry. For macrotubes and macrobeams synthesized from Pt²⁻:Pt²⁺:Cu²⁺ salt ratios of 1:1:0, 2:1:1, 3:1:2, and 1:0:1, DMAB reduced 3:1:2 macrotubes demonstrated the highest ethanol oxidation peak currents of 12.0 A/g at 0.5 mV/s and is attributed to the combination of a highly porous structure and platinum enriched surface. Salt templates with electrochemical reduction are suggested as a rapid, scalable, and tunable platform to achieve a wide range of 3-dimensional porous metal, alloy, and multi-metallic nanomaterials for catalysis, sensor, and energy storage applications. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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13 pages, 10479 KiB

Open AccessArticle

Monodispersed Pt₃Ni Nanoparticles as a Highly Efficient Electrocatalyst for PEMFCs

by Delong Yang, Jun Gu, Xiaomeng Liu, Haitong He, Meiyu Wang, Peng Wang, Yong Zhu, Qi Fan and Runsheng Huang

Catalysts 2019, 9(7), 588; https://doi.org/10.3390/catal9070588 - 05 Jul 2019

Cited by 13 | Viewed by 3459

Abstract

A facile strategy is proposed to synthesize monodispersed Pt₃Ni nanoparticles. Such a kind of electrocatalyst shows a larger electrochemical surface area (98.9 m² g_pt⁻¹) and double the mass activity of the oxygen reduction reaction activity compared to [...] Read more.

A facile strategy is proposed to synthesize monodispersed Pt₃Ni nanoparticles. Such a kind of electrocatalyst shows a larger electrochemical surface area (98.9 m² g_pt⁻¹) and double the mass activity of the oxygen reduction reaction activity compared to commercial Pt/C catalyst. The results show that the suitable addition of Ni and triethylamine in the reduction process plays an important role in controlling the size and dispersion of Pt₃Ni nanoparticles. A further membrane electrode assembly test proves that as-prepared Pt₃Ni nanoparticles can greatly enhance the electrochemical performance of a proton exchange membrane fuel cell, which exhibits a great potential of application in fuel cells. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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14 pages, 2956 KiB

Open AccessArticle

Selective Hydrogenation of 3-Nitrostyrene over a Co-promoted Pt Catalyst Supported on P-containing Activated Charcoal

by Qifan Wu, Chao Zhang, Weiwei Lin, Haiyang Cheng, Masahiko Arai and Fengyu Zhao

Catalysts 2019, 9(5), 428; https://doi.org/10.3390/catal9050428 - 08 May 2019

Cited by 6 | Viewed by 3333

Abstract

A series of Co-modified Pt catalysts supported on P-containing activated charcoal were studied for the selective hydrogenation of 3-nitrostyrene (NS) to 3-aminostyrene (AS). The addition of Co decreased the rate of hydrogenation but enhanced the selectivity to AS, being 92% at nearly 100% [...] Read more.

A series of Co-modified Pt catalysts supported on P-containing activated charcoal were studied for the selective hydrogenation of 3-nitrostyrene (NS) to 3-aminostyrene (AS). The addition of Co decreased the rate of hydrogenation but enhanced the selectivity to AS, being 92% at nearly 100% conversion over an optimized catalyst. The high AS selectivity should result from the configuration of NS adsorption on the catalyst, which occurs preferentially with its -NO₂ group on the Pt–PO_x interface layer over the surface of supported Pt particles. The formation of such a Pt–PO_x area is promoted by the Co additive. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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15 pages, 2402 KiB

Open AccessArticle

Oxychlorination Redispersion of Pt Catalysts: Surface Species and Pt-Support Interactions Characterized by X-ray Absorption and FT-IR Spectroscopy

by Chia-Ching Hung, Cheng-Yang Yeh, Cheng-Chieh Shih and Jen-Ray Chang

Catalysts 2019, 9(4), 362; https://doi.org/10.3390/catal9040362 - 15 Apr 2019

Cited by 5 | Viewed by 4662

Abstract

To help elucidate the oxychlorination redispersion reaction mechanism, the surface species formed on the surface of γ-Al₂O₃ was characterized by X-ray absorption spectroscopy (XAS). The efficacy of redispersion was assessed by the Pt–Pt coordination number (CN_Pt–Pt) of redispersed, [...] Read more.

To help elucidate the oxychlorination redispersion reaction mechanism, the surface species formed on the surface of γ-Al₂O₃ was characterized by X-ray absorption spectroscopy (XAS). The efficacy of redispersion was assessed by the Pt–Pt coordination number (CN_Pt–Pt) of redispersed, and then reduced samples. A nearly fully redispersed complex (Pt_rd52) was prepared by treating a sintered model Pt/γ-Al₂O₃ catalyst at 520 °C, Air/EDC (ethylene dichloride) of 30, and WHSV (Weight Hourly Space Velocity) of 0.07 h⁻¹ for 16 h. For investigating temperature effects, samples treated at 460 (Pt_rd46) and 560 °C (Pt_rd56) were also prepared for comparison. It was found that, while an octahedral resembling Pt(O_s)_3–4(O–Cl)_2–3 (O_s represents support oxygen or hydroxyl oxygen) complex was formed on γ-Al₂O₃ of Pt_rd52, less O–Cl ligands were formed on the redispersed complexes, Pt_rd46 and Pt_rd56. A negative correlation of CN_Pt–Pt with CN_Pt–Cl* (Cl* represents the Cl atom in O–Cl ligand) for these three samples further suggested that the formation of Pt–O–Cl played a key role in the redispersion process. Pt–O–Cl could be formed in the reaction of reactive Cl⋅ and PtO₂. At an operation temperature of lower-than-optimal temperatures of 520 °C, less Cl₂ dissociation and less O–Cl ligands were formed. On the other hand, higher temperatures may facilitate Cl₂ dissociation, but reduce the equilibrium conversion of HCl to Cl₂, leading to increased HCl reaction with Pt (PtO₂) clusters to form Pt–Cl (Cl is the atom bonded directly to Pt), and decreased formation of Pt–O–Cl. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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14 pages, 2920 KiB

Open AccessFeature PaperArticle

Exploiting the Synergetic Behavior of PtPd Bimetallic Catalysts in the Selective Hydrogenation of Glucose and Furfural

by Priscilla M. de Souza, Lishil Silvester, Anderson G. M. da Silva, Cibele G. Fernandes, Thenner S. Rodrigues, Sebastien Paul, Pedro H. C. Camargo and Robert Wojcieszak

Catalysts 2019, 9(2), 132; https://doi.org/10.3390/catal9020132 - 01 Feb 2019

Cited by 17 | Viewed by 4060

Abstract

Mono and bimetallic catalysts based on Pt and Pd were prepared by a co-precipitation method. They were tested in liquid phase hydrogenation reactions of glucose and furfural at low temperature and pressure. The bimetallic PtPd/TiO₂ catalyst proved to be an efficient material [...] Read more.

Mono and bimetallic catalysts based on Pt and Pd were prepared by a co-precipitation method. They were tested in liquid phase hydrogenation reactions of glucose and furfural at low temperature and pressure. The bimetallic PtPd/TiO₂ catalyst proved to be an efficient material in selectively hydrogenating glucose to sorbitol. Moreover, high furfural conversion was attained under relatively soft conditions, and the furfuryl alcohol selectivity was strongly affected by the chemical composition of the catalysts. Furfuryl alcohol (FA) was the major product in most cases, along with side products such as methylfuran (MF), furan, and traces of tetrahydrofuran (THF). These results showed that the PtPd bimetallic sample was more active relative to the monometallic counterparts. A correlation between the catalytic results and the physicochemical properties of the supported nanoparticles identified key factors responsible for the synergetic behavior of the PtPd system. The high activity and selectivity were due to the formation of ultra-small particles, alloy formation, and the Pt-rich surface composition of the bimetallic particles supported on the TiO₂ nanowires. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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13 pages, 3312 KiB

Open AccessArticle

Synthesis, Characterization and CO Tolerance Evaluation in PEMFCs of Pt₂RuMo Electrocatalysts

by Martin González-Hernández, Ermete Antolini and Joelma Perez

Catalysts 2019, 9(1), 61; https://doi.org/10.3390/catal9010061 - 09 Jan 2019

Cited by 19 | Viewed by 4491

Abstract

Pt₂RuMo/C catalysts were synthesized by the modified polyol method in the presence and absence of Li(C₂H₅)₃BH (LBH), annealed at 600 °C under H₂ atmosphere to improve the reduction of Pt and Ru to provide [...] Read more.

Pt₂RuMo/C catalysts were synthesized by the modified polyol method in the presence and absence of Li(C₂H₅)₃BH (LBH), annealed at 600 °C under H₂ atmosphere to improve the reduction of Pt and Ru to provide stronger interactions between Mo and another metals. LBH affected the physico-chemical characteristics of Pt₂RuMo, that is, in the presence of LBH an increment of Mo(IV) amount and a decrease in the PtRu alloying degree were observed. The catalytic activity for hydrogen oxidation in the presence and absence of CO (CO tolerance) of the Pt₂RuMo/C catalysts as anodes in polymer electrolyte membrane fuel cells (PEMFCs) was compared to that of a commercial PtRu/C catalyst. The results indicated that the CO tolerance increased with an increase in Mo(IV) content, but the stability increased with an increment of the amount of Ru oxides in the catalysts. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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18 pages, 5386 KiB

Open AccessArticle

Plasma-Assisted Surface Interactions of Pt/CeO₂ Catalyst for Enhanced Toluene Catalytic Oxidation

by Bingxu Chen, Bangfen Wang, Yuhai Sun, Xueqin Wang, Mingli Fu, Junliang Wu, Limin Chen, Yufei Tan and Daiqi Ye

Catalysts 2019, 9(1), 2; https://doi.org/10.3390/catal9010002 - 21 Dec 2018

Cited by 32 | Viewed by 4443

Abstract

The performance of plasma-modified Pt/CeO₂ for toluene catalytic oxidation was investigated. Pt/CeO₂ nanorods were prepared by wet impregnation and were modified by thermal (PC-T), plasma (PC-P), and combined (PC-TP and PC-PT) treatments. The modified catalysts were characterized by TEM (transmission electron [...] Read more.

The performance of plasma-modified Pt/CeO₂ for toluene catalytic oxidation was investigated. Pt/CeO₂ nanorods were prepared by wet impregnation and were modified by thermal (PC-T), plasma (PC-P), and combined (PC-TP and PC-PT) treatments. The modified catalysts were characterized by TEM (transmission electron microscope), BET (Brunauer-Emmett-Teller), H₂-TPR, O₂-TPD, XPS, UV-Raman, and OSC tests. The significant variation of the surface morphologies and surface oxygen defects could have contributed to the modification of the Pt/CeO₂ catalysts via the plasma treatment. It was found that plasma could promote the surface interaction between Pt and CeO₂, resulting in the thermal stability of the catalyst. The Pt-Ce interaction was also conducive to an increase in the number of oxygen vacancies. Furthermore, PC-PT and PC-TP showed a significant difference in oxygen vacancy concentrations and catalytic activities, which illustrated that the treatment sequence (plasma and thermal treatment) affected the performance of Pt/CeO₂. The PC-PT sample showed the highest catalytic activity with T₁₀₀ at 205 °C. This work thus demonstrates that plasma in combined treatment sequences could assist surface interactions of catalysts for enhanced toluene catalytic oxidation. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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15 pages, 5854 KiB

Open AccessArticle

The Modification of Pt/Graphene Composites with Oxophilic Metal Bi (Bi₂O₃) and Its Dual-Functional Electro-Photo Catalytic Performance

by Yingli Wu, Xiuyun Duan, Zhongshui Li, Shuhong Xu, Yixin Xie, Yufei Lai and Shen Lin

Catalysts 2018, 8(10), 465; https://doi.org/10.3390/catal8100465 - 17 Oct 2018

Cited by 7 | Viewed by 3640

Abstract

The Pt-Bi (Bi₂O₃)/GNs (PVP) composite was synthesized using aqueous solution synthesis and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and Raman spectroscopy. It was found that the [...] Read more.

The Pt-Bi (Bi₂O₃)/GNs (PVP) composite was synthesized using aqueous solution synthesis and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and Raman spectroscopy. It was found that the water-soluble polyvinyl pyrrolidone (PVP) helped to tune the particles’ morphology, resulting in a uniform distribution of Pt-Bi nanoclusters on the surface of graphene. Cyclic voltammetry, chronoamperometry and linear scanning voltammetry (LSV) were used to study the electrocatalytic properties towards a methanol oxidation reaction (MOR) and an oxygen reduction reaction (ORR). The results show that Pt-Bi (Bi₂O₃)/GNs (PVP) exhibits superior bifunctional electrocatalytic properties for both MOR and ORR, mainly due to the introduction of oxophilic Bi species and the better dispersion of the Pt-Bi nanoclusters. In particular, the electro-photo catalysis for both MOR and ORR occurred under simulated sunlight irradiation due to the existence of photo-responsive Bi species, which is helpful for converting solar energy into electric energy during a traditional electrocatalytic process. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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Review

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24 pages, 3932 KiB

Open AccessReview

Low Pt Alloyed Nanostructures for Fuel Cells Catalysts

by Shuoyuan Huang, Aixian Shan and Rongming Wang

Catalysts 2018, 8(11), 538; https://doi.org/10.3390/catal8110538 - 13 Nov 2018

Cited by 15 | Viewed by 5391

Abstract

Low-noble metal electrocatalysts are attracting massive attention for anode and cathode reactions in fuel cells. Pt transition metal alloy nanostructures have demonstrated their advantages in high performance low-noble metal electrocatalysts due to synergy effects. The basic of designing this type of catalysts lies [...] Read more.

Low-noble metal electrocatalysts are attracting massive attention for anode and cathode reactions in fuel cells. Pt transition metal alloy nanostructures have demonstrated their advantages in high performance low-noble metal electrocatalysts due to synergy effects. The basic of designing this type of catalysts lies in understanding structure-performance correlation at the atom and electron level. Herein, design threads of highly active and durable Pt transition metal alloy nanocatalysts are summarized, with highlighting their synthetic realization. Microscopic and electron structure characterization methods and their prospects will be introduced. Recent progress will be discussed in high active and durable Pt transition metal alloy nanocatalysts towards oxygen reduction and methanol oxidation, with their structure-performance correlations illustrated. Lastly, an outlook will be given on promises and challenges in future developing of Pt transition metal alloy nanostructures towards fuel cells catalysis uses. Full article

(This article belongs to the Special Issue Recent Advances in Pt-Based Catalysts: Theoretical and Experimental Results)

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