ZrO2 anchored core-shell Pt–Co alloy particles through direct pyrolysis of mixed Pt–Co–Zr salts for improving activity and durability in proton exchange membrane fuel cells

Highly active and durable Pt-based catalysts for oxygen reduction reaction (ORR) are very important and necessary for the proton exchange membrane fuel cells (PEMFCs). In this paper, we report the preparation and performance study of ORR catalysts composed of core-shell Pt–Co alloy nanoparticles (NPs) on multi-walled carbon nanotubes (MWCNTs) anchored with ZrO₂ NPs (denoted as Pt–Co–ZrO₂/MWCNTs). Thanks to the unique three-phase structure, the mass activity of Pt–Co–ZrO₂/MWCNTs for ORR at 0.9 V versus reversible hydrogen electrode (RHE) is1577 mA mg_Pt^?1, which is ～6.6-fold higher than that of the commercial Pt/C (238 mA mg_Pt^?1). After 50,000 cycles for durability test, the mass activity of Pt–Co–ZrO₂/MWCNTs for ORR remained 88% of its initial value. In stark contrast, that of Pt/C kept only about 56.3% of its initial value. More importantly, its catalytic performance was fully observed/verified in a H₂-air PEMFC single cell test. When the Pt loading of Pt–Co–ZrO₂/MWCNTs loaded cathode was one fourth of that with commercial Pt/C as the cathode catalyst, comparable cell performance was achieved. More impressively, the MEA with Pt–Co–ZrO₂/MWCNTs underwent only 24.5% degradation in maximum power density after 30,000 accelerated durability tests (ADTs). However, the MEA with Pt/C after 30,000 ADTs exhibited 39.6% performance loss in maximum power density. The enhanced mass activity and catalytic durability of Pt–Co–ZrO₂/MWCNTs could be attributed to the core-shell Pt–Co alloy NPs with Pt-rich surface and the interface effect between Pt–Co alloy NPs and oxygen vacancy-rich ZrO₂ NPs. In addition, this research also provided a solution to the durability issue of cathodes without sacrificing ORR mass activity, which would promote practical application of PEMFCs.     

Surfactant-assisted synthesis of platinum nanoparticle catalysts for proton exchange membrane fuel cells

High-performance platinum nanoparticle catalysts (Pt–NPCs) remain the most widespread applied electrocatalysts for oxygen reduction reaction (ORR). Here, cetyltrimethylammonium bromide (CTAB), a surface-controlling agent, is introduced to modulate the microstructure and size of Pt nanoparticles (NPs) via a microwave-assisted heating process. The Pt-NPC assisted by 5 wt% CTAB exhibits the highest mass activity (MA) of 0.072 A mg_Pt^?1 and specific activity (SA) of 0.077 mA cm^?2, higher than those of commercial Pt/C (0.023 A mg_Pt^?1 and 0.035 mA cm^?2). Transmission electron microscopy (TEM) results indicate that Pt NPs are uniformly dispersed onto carbon supports with an average size of 2.39 nm. When applied in membrane electrode assembly (MEA), it exhibits the highest power density of 1.142 W cm^?2, which is about 1.24 times larger than that of commercial Pt/C.     

Pt–Co nanoparticles anchored by ZrO2 for highly efficient and durable oxygen reduction reaction in H2-air fuel cells

Synthesis of Pt-based catalysts with high activity and durability for oxygen reduction reaction (ORR) remains a very challenging task in the field of fuel cells. Here, Co-doped Pt nanoparticles (NP) with surface-defect ZrO₂ are supported on the multi-walled carbon nanotubes (MWCNTs) (denoted as Pt–Co + ZrO₂/MWCNTs). The Pt–Co + ZrO₂/MWCNTs displays an ORR mass activity of 0.98 A mg_Pt^?1 at 0.9 V, which is 4.1-fold higher than that of the commercial Pt/C (0.238 A mg_Pt^?1). Further durability test shows that the Pt–Co + ZrO₂/MWCNTs remains nearly unchanged ORR mass activity after 50000 accelerated durability testings (ADTs). Based on the mass performance and surface performance, the fuel cell with Pt–Co + ZrO₂/MWCNTs cathode has far better power performance than that with commercial Pt/C. Moreover, the fuel cell with Pt–Co + ZrO₂/MWCNTs cathode undergo only a 6.1% maximum power loss after 50000 ADTs. However, that with commercial Pt/C cathode after 30000 ADTs has 39.6% maxinum power loss. More impressively, compared to the 220 mV loss of Pt/C after 30000 ADTs, the Pt–Co + ZrO₂/MWCNTs cathode also displays only 20 mV loss at 0.8 A/cm² after 50000 ADTs. The enhanced intrinsic activity of Pt–Co + ZrO₂/MWCNTs may be attributed to the Co-doped Pt NPs and interface effect of Co-doped Pt NPs and surface defect-rich ZrO₂.     

PtCo incorporated porous carbon nanofiber as a promising oxygen reduction electrocatalyst

Designing oxygen reduction reaction (ORR) catalysts with high activity and long durability is significant for the development of proton exchange membrane fuel cells. Herein, the optimized platinum nanowires are used as templates for inducing growth of cobalt-containing metal-organic framework, deriving uniform nanofibers. After the calcination, the metal ions are transferred into the nitrogen-rich porous carbon, and wrapped by the carbon skeleton to form the PtCo bimetal incorporated nanofibers as high-performance ORR electrocatalyst. The Pt₄Co@NC-900 catalyst yields high specific activity (1.37 mA cm⁻²) in comparison to Pt/C (0.38 mA cm⁻²). The mass activity (MA) of Pt₄Co@NC-900 catalyst is approximately 3.8-fold higher than that of the commercial Pt/C under acidic conditions. After the accelerated durability tests, the Pt₄Co@NC-900 catalyst presents only 16% loss in MA, while Pt/C catalyst retains 73.0% of the initial MA. The improved ORR performance can be ascribed to the synergistic interaction between Co and Pt.     

ZIF derived mesoporous carbon frameworks with numerous edges and heteroatom-doped sites to anchor nano-Pt electrocatalyst

We report the use of nitrogen-doped three-dimensional carbon frameworks (N-MCF) to promote the catalytic performance of nano-sized Pt electrocatalyst for the catalysis of oxygen reduction reaction (ORR). The N-MCF, obtained by pyrolysis of zeolitic imidazolate framework, provides abundant edges, defects, and heteroatom-doped sites to anchor Pt nanoparticles, leading to strong Pt-support interaction and excellent particle dispersion within its three-dimensional mass transport channels. Electrochemical results show only 8 mV degradation in the half-wave potential after accelerated durability test for the N-MCF supported Pt catalysts. Meanwhile, the mass activity and specific activity of Pt/N-MFC could reach 246 mA mg⁻¹_Pt and 0.276 mA cm⁻² at 0.90 V_RHE, which is better than that of commercial Pt/C. Moreover, the high Pt utilization of Pt/N-MFC (186 mg _Pt kW⁻¹) could reach 1.9 times than that of fuel cell fabricated with commercial Pt/C cathode.     

Cu-template-dependent synthesis of PtCu nanotubes for oxygen reduction reactions

The development of electrocatalysts with high activity and durability for oxygen reduction reaction (ORR) in acidic electrolyte environments remains a serious challenge for clean and efficient energy conversion. Synergistic effects between Pt and inexpensive metals, the d band center of Pt and catalyst morphology could adjust the adsorption and desorption of oxygen intermediates by the Pt. All the factors affect the catalytic performance of Pt-based nanocrystals. Here, we prepared Cu@PtCu₃ NWs with an average diameter of 74.9 nm for Cu and about 10 nm PtCu₃ layer. After etching, the Cu@PtCu₃ nanowires is transformed into PtCu nanotube structure, due to the removal of copper from the surface and interior. PtCu NTs for ORR shows excellent activities and durability due to the integration of structural advantages and synergistic effects. Notably, the mass activity and specific activity of PtCu NTs (0.105 A mg^?1_Pt and 0.230 mA cm^?2_Pt) are 2.0 and 3.8 times higher than that of commercial Pt/C (0.053 A mg^?1_Pt and 0.06 mA cm^?2_Pt). The etching process to change the morphology of the catalyst and alter the electronic structure of the catalyst is expected to be useful for the design of future structured Pt-based alloy nanocatalysts.     

Bimetallic Pt3Mn nanowire network structures with enhanced electrocatalytic performance for methanol oxidation

Pt-based catalysts are still most attractive and could be the major driving force for facile electrochemical reactions in direct methanol fuel cells (DMFCs). In this work, a Pt₃Mn nanowire network structures (NWNs) catalyst was successfully synthesized by a soft template (CTAB) method. The morphology and elemental composition of the Pt₃Mn NWNs were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The electrocatalytic behavior of the synthesized Pt₃Mn NWNs catalyst towards methanol oxidation reaction (MOR) was studied by cyclic voltammetry (CV) and chronoamperometry (CA). The results reveal that the Pt₃Mn NWNs has superior MOR activity and durability compared to Pt NWNs and commercial Pt/C. The mass and specific activities of Pt₃Mn NWNs are 0.843 A mg⁻¹ and 1.8 mA cm⁻² respectively, which are twice that of commercial Pt/C. Additionally, the results of CA test indicate that the Pt₃Mn NWNs possesses better durability than Pt NWNs and commercial Pt/C catalysts in acidic media, which is expected to be a new alternative anode material in DMFCs.     

Highly efficient electrocatalysts for oxygen reduction reaction: Nitrogen-doped PtNiMo ternary alloys

The relatively low efficiency of the reaction of oxygen reduction (ORR) remains among the main obstacles for hydrogen fed proton exchange membrane fuel cells (H-PEMFCs) commercialization.In the present work, PtNiMo ternary alloy catalysts are obtained through reducing by NaBH₄ and subsequent thermal annealing in NH₃ at 1.0 atm. The as prepared catalysts are physico-chemically (XRD, TEM and XPS) characterized, exhibiting alloy nanostructure.From the electrochemical tests it is found that they exhibit high ORR activity in aqueous solutions saturated with O₂ and acidified with HClO₄. From the as synthesized catalysts, Pt₃Ni₃MoN/C shows the highest mass activity (539.41 mA mg⁻¹ Pt); 3.5 times greater than that observed over commercial Pt/C (154.46 mA mg⁻¹ Pt). Moreover, they show very good stability, while their ORR activity is only slightly altered after 5,000 cycles.These highly performing and low cost catalysts could thus open up new possibilities for the commercialization of hydrogen fed PEMFCs.     

Facile one-pot aqueous fabrication of interconnected ultrathin PtPbPd nanowires as advanced electrocatalysts for ethanol oxidation and oxygen reduction reactions

The catalytic features of Pt-based advanced materials closely correlate with the compositions, morphology and structure. Hence, interconnected trimetallic PtPbPd ultrathin nanowires (PtPbPd NWs) were synthesized by octylphenoxypolyethoxyethanol (NP-40)-mediated one-pot aqueous method, using in-situ generated hydrogen bubbles as the dynamic template. It is found that the types of the precursors and the amount of NP-40 are critical in this synthesis. The as-obtained architectures showed remarkable improvement in the electrocatalytic properties for ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR), surpassing those of commercial Pt/C (20 wt%), homemade PtPd NWs, PtPb NWs and PdPb NWs. Specifically, the mass activity (MA)/specific activity (SA) of PtPbPd NWs (1.20 A mg⁻¹/2.78 mA cm⁻²) is higher than those of Pt/C (0.86 A mg⁻¹/1.79 mA cm⁻²) in 0.5 M KOH solution. Furthermore, the as-synthesized catalyst displayed a positive-shift of the onset potential (E_onset, 0.993 V) for ORR over Pt/C (0.895 V) in 0.1 M KOH electrolyte. These scenarios manifest that this approach provides some new valuable guidelines for preparing novel trimetallic nanocatalysts in energy storage and conversion applications.     

Synthesis of ultrathin-wall PtCu nanocages as efficient electrocatalyst toward oxygen reduction reactivity

Pt-based hollow nanocrystals have shown an astonishing performance toward oxygen reduction reaction (ORR) because of their open structures, high surface areas and large Pt atom utilization. However, the careful geometric control of hollow nanocrystals is still not easy. Here, a facile template-free method was reported for the synthesis of ultrathin-wall PtCu nanocages with small islands on the surface (U–PtCu NCs). Moreover, the wall thickness of nanocages and the density of islands were well-tuned by controlling the experiment conditions. In the end, the novel hollow structures with abundant defects as well as the synergistic interaction between Pt and Cu elements endowed U–PtCu NCs with enhanced ORR activity. Specifically, its mass activity was 0.36 A mg⁻¹ and its specific activity was 0.71 mA cm⁻², which were about 4.2 and 7.1 times higher than that of commercial Pt/C. In addition, the enhanced stability was proved by the accelerated durability test of 10 000 cycles.     

Enhanced oxygen reduction activity of PtCu nanoparticles by morphology tuning and transition-metal doping

Developing active and durable electrocatalysts for oxygen reduction reaction (ORR) is of great significance in proton exchange membrane fuel cells (PEMFCs). Herein, we develop a facile strategy to synthesize PtCu nanoparticles with enhanced ORR performance through morphology tuning and transition-metal doping. Two distinct PtCu nanoparticles, namely nanooctahedrons (NOs) and nanospheres (NSs), are selectively synthesized in presence or absence of W(CO)₆ via a facile one-pot method. Furthermore, by introducing a small amount of third transition metal, M-doped (M = Sc, Y, La, Gd, Fe) PtCu NOs are obtained. Electrocatalytic results suggest that the ORR performance of PtCu NOs is better than that of PtCu NSs due to the morphology advantages. And the ORR performance of PtCuM NOs is further promoted since the doping effect of transition metals compared to that of PtCu NOs. Particularly, PtCuSc NOs exhibit remarkable mass activity (1.652 mA μg⁻¹_Pt) and specific activity (2.093 mA cm⁻²), which are 9.9 and 7.2 times higher than that of commercial Pt/C catalysts at 0.8 V (vs. RHE). Moreover, after accelerated stability tests, the loss of mass activity for PtCuSc NOs is only 9.2%, which is much lower than that of PtCu NOs (16.5%) and commercial Pt/C (44.3%). This work provides a feasible idea to boost the ORR performances of Pt-based nanoparticles.     

Binary CuPt alloy nanoparticles assembled on reduced graphene oxide-carbon black hybrid as efficient and cost-effective electrocatalyst for PEMFC

Addressed herein is the synthesis of binary CuPt alloy nanoparticles (NPs), their assembly on reduced graphene oxide (rGO), Vulcan XC72 (VC) and their hybrid (rGO-VC) to be utilized as electrocatalysts for fuel cell reactions (HOR and ORR) in acidic medium and PEMFC tests. The synthesis of nearly-monodisperse Cu₄₅Pt₅₅ alloy NPs was achieved by using a chemical reduction route comprising the reduction of commercially available metal precursors in a hot surfactant solution. As-synthesized Cu₄₅Pt₅₅ alloy NPs were then assembled on three support materials, namely rGO, VC and rGO-VC) via liquid phase self-assembly method. After the characterization, the electrocatalysts were prepared by mixing the yielded materials with Nafion and their electrocatalysis performance was investigated by studying CV and LSV for HOR and ORR in acidic medium. Among the three electrocatalysts tested, Cu₄₅Pt₅₅/rGO-VC hybrid showed the highest catalytic activity with ECSA of 119 m² g⁻¹ and mass activity of 165 mA mg⁻¹_Pt. After the evaluation of electrochemical performance of the three prepared electrocatalysts, their performance was then evaluated in fuel cell conditions. In similar to electrochemical activities, the Cu₄₅Pt₅₅/rGO-VC hybrid electrocatalyst showed a superior fuel cell performance and power output by providing a maximum power of 480 mW cm⁻² with a relatively low Pt loading (0.28 mg cm⁻²). Additionally, the Cu₄₅Pt₅₅/rGO-VC hybrid electrocatalyst exhibited substantially better activity as compared to Pt/rGO-VC electrocatalyst. Therefore, the present study confirmed that alloying Pt with Cu enhances the catalytic activity of Pt metal along with the help of beneficial features of rGO-VC hybrid support material. It should be noted that this is the first example of studying PEMFC performance of CuPt alloy NPs supported on rGO, VC and rGO-VC hybrid.     

Feasibility of ultra-low Pt loading electrodes for high temperature proton exchange membrane fuel cells based in phosphoric acid-doped membrane

Factors as the Pt/C ratio of the catalyst, the binder content of the electrode and the catalyst deposition method were studied within the scope of ultra-low Pt loading electrodes for high temperature proton exchange membrane fuel cells (HT-PEMFCs). The Pt/C ratio of the catalyst allowed to tune the thickness of the catalytic layer and so to minimize the detrimental effect of the phosphoric acid flooding. A membrane electrode assembly (MEA) with 0.05 mg_Ptcm⁻² at anode and 0.1 mg_Ptcm⁻² at cathode (0.150 mg_Ptcm⁻² in total) attained a peak power density of 346 mW cm⁻². It was proven that including a binder in the catalytic layer of ultra-low Pt loading electrodes lowers its performance. Electrospraying-based MEAs with ultra-low Pt loaded electrodes (0.1 mg_Ptcm⁻²) rendered the best (peak power density of 400 mW cm⁻²) compared to conventional methods (spraying or ultrasonic spraying) but with the penalty of a low catalyst deposition rate.     

Facile construction of 3D hyperbranched PtRh nanoassemblies: A bifunctional electrocatalyst for hydrogen evolution and polyhydric alcohol oxidation reactions

Development of highly effective and stable electrocatalysts is urgent for various energy conversion applications. Herein, a facile co-reduction approach was developed to fabricate three-dimensional (3D) hyperbranched PtRh nanoassemblies (NAs) under solvothermal conditions, where creatinine and cetyltrimethylammonium chloride (CTAC) were employed as the structure-directing agents. The as-synthesized nanocatalyst exhibited intriguing catalytic characters for hydrogen evolution reduction (HER) with a low overpotential (20 mV) at 10 mA cm⁻² and a small Tafel slope (49.01 mV dec⁻¹). Meanwhile, the catalyst showed remarkably enlarged mass activity (MA: 2.16/2.02 A mg⁻¹) and specific activity (SA: 4.16/3.88 mA cm⁻²) towards ethylene glycol and glycerol oxidation reactions (EGOR and GOR) alternative to commercial Pt black and homemade Pt₃Rh nanodendrites (NDs), PtRh₃ NDs and Pt nanoparticles (NPs). This method offers a feasible platform to fabricate bifunctional, efficient, durable and cost-effective nanocatalysts with finely engineered structures and morphologies for renewable energy devices.     

Platinum supported on hydroxyl-grafted poly (3,4-ethylenedioxythiophene)-modified RuCo,N-tridoped bamboo-like carbon nanotubes for direct methanol fuel cell

The development of highly active and efficient heterogeneous catalytic oxidation system has become an attractive research field. In this paper, a catalyst (RuCo/N-CNT@PEDOT-OH/Pt) from platinum nanoparticles (Pt NPs) supported on hydroxyl-grafted poly(3,4-ethylenedioxythiophene) (PEDOT–OH)-modified RuCo, N-tridoped bamboo-like carbon nanotubes (RuCo/N-CNT) are used for direct methanol fuel cell (DMFC). The electrocatalytic activity of RuCo/N-CNT@PEDOT-OH/Pt is systematically compared with RuCo/N-CNT/Pt (Pt NPs supported on RuCo/N-CNT without PEDOT-OH) in the methanol oxidation reaction (MOR). The growth mechanism of carbon nanotubes and the role of heteroatom doping in the electrocatalytic process is explored. The catalysts show excellent electrocatalytic performance with high stability for MOR. It is found that the mass activity (MA) of the RuCo/N-CNT@PEDOT-OH/Pt (1961.3 mA mg^?1_Pt) for MOR was higher than that of RuCo/N-CNT/Pt (1470.1 mA mg^?1_Pt) and the commercial Pt/C catalysts (281.0 mA mg^?1_Pt), indicating the positive effect of the PEDOT-OH in the electrocatalytic MOR. In addition, density functional theory (DFT) calculations verify the possible mechanism pathways of the obtained RuCo/N-CNT@PEDOT-OH/Pt catalyst. This presented catalyst offers new inspiration for designing efficient electrocatalysts for methanol oxidation.     

An effective electrocatalyst based on platinum nanoparticles supported with graphene nanoplatelets and carbon black hybrid for PEM fuel cells

A facile synthesis at room temperature and at solid-state directly on the support yielded small, homogeneous and well-dispersed Pt nanoparticles (NPs) on CB-carbon black, GNP-graphene nanoplatelets, and CB-GNP-50:50 hybrid support. Synthesized Pt/CB, Pt/GNP and Pt/CB:GNP NPs were used as electrocatalysts for polymer electrolyte membrane fuel cell (PEMFC) reactions. HRTEM results displayed very small, homogeneous and well-dispersed NPs with 1.7, 2.0 and 4.2 nm mean-diameters for the Pt/CB-GNP, Pt/GNP and Pt/CB electrocatalysts, respectively. Electrocatalysts were also characterized by RAMAN, XRD, BET and CV techniques. ECSA values indicated better activity for graphene-based supports with 19 m² g⁻¹_Pt for Pt/GNP and 55 m² g⁻¹_Pt for Pt/CB-GNP compared to 10 m² g⁻¹_Pt for Pt/CB. Oxygen reduction reaction (ORR) studies and fuel cell tests were in parallel with these results where highest maximum power density of 377 mW cm⁻² was achieved with Pt/CB-GNP hybrid electrocatalyst. Both fuel cell and ORR studies for Pt/CB-GNP indicated better dispersion of NPs on the support and efficient fuel cell performance that is believed to be due to the prevention of restacking of GNP by CB. To the best of our knowledge, Pt/GNP and Pt/CB-GNP electrocatalysts are the first in literature to be synthesized with the organometallic mild synthesis method using Pt(dba)₃ precursor for the PEMFC applications.     

MoO2 nanocrystals down to 5 nm as Pt electrocatalyst promoter for stable oxygen reduction reaction

The single molybdenum oxide (MoO₂) crystals down to 5 nm in diameter on carbon (denoted as C-MoO₂) are synthesized based on ion-exchange principle for the first time. The structures, morphologies, chemical and electrocatalytic performances of as-synthesized nanomaterials are characterized by physical, chemical and electrochemical methods. The results indicate that electrocatalysts made with Pt nanoparticles supporting on C-MoO₂ (denoted as Pt/C-MoO₂) are highly active and stable for oxygen reduction reaction (ORR) in fuel cells. A mass activity of 187.4 mA mg⁻¹_Pt at 0.9 V is obtained for ORR, which is much higher than that on commercial Pt/C (TKK) electrocatalyst (98.4 mA mg⁻¹_Pt). Furthermore, the electrochemical stability of Pt/C-MoO₂ is more excellent than that of Pt/C (TKK). The origin of the improvement in catalytic activity can be attributed to the synergistic or promotion effect of MoO₂ on Pt. The improvement in electrochemical stability is due to the strong interaction force between Pt and MoO₂.     

Highly active and durable carbon support Pt-rare earth catalyst for proton exchange membrane fuel cell

Pt-rare earth catalysts are highly efficient novel electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) due to their high stability and activity. In this study, we prepare Pt-YO_x/C catalysts using the traditional wet chemical reduction method. The optimal quantity of Y-oxides loaded onto the Pt/C surface is determined based on electrochemical performance using linear sweep voltammetry (LSV) and cyclic voltammetry (CV) methods. After accelerated durability tests (ADT), the remnant electrochemical surface area (ECSA) and mass active (MA) in Pt-YO_x/C catalyst are relatively higher compared to the commercial Pt/C (JM). In the single-cell test, the maximum mass power densities of the MEAs prepared by self-made Pt-YO_x/C and Pt/C (JM) catalysts in cathodes record at 1895 and 1371 mW mg_Pt⁻¹, respectively, which shows a successful increment in platinum utilization. These results indicate that Pt-YO_x/C catalyst can potentially improve the durability and lower the cost of PEMFCs.     

Photodeposition of Pt nanoparticles onto TiO2@CNT as high-performance electrocatalyst for oxygen reduction reaction

The commonly used Pt/C catalyst has low durability for oxygen reduction reaction (ORR). In this work, CNT-supported TiO₂ nanoparticles, which synergistically combines the merits of TiO₂ (high stability and strong interactions with the supported Pt nanoparticles) and CNT (high specific surface area and large electrical conductivity), are prepared by a sol-gel process coupled with an annealing process and used as the support for Pt nanoparticles, which are anchored around TiO₂ nanoparticles by a photodeposition technique. The as-synthesized Pt/TiO₂@CNT catalyst exhibits a mass activity 5.3 times as large as that of the commercial Pt/C catalyst (0.358 A mg_Pt⁻¹ vs. 0.067 A mg_Pt⁻¹ at 0.9 V) and an excellent stability (no activity loss after 10000 potential cycles) for ORR, which can be mainly attributed to the lower oxygen adsorption energy of Pt, resulting from the strong metal-support interaction induced by the deposition of Pt nanoparticles around the well-dispersed TiO₂ nanoparticles on CNT.     

Composition-tunable PtCu porous nanowires as highly active and durable catalyst for oxygen reduction reaction

To accelerate the commercialization of fuel cells, many efforts have been made to develope highly active and durable Pt-based catalyst for oxygen reduction reaction (ORR). Herein, PtCu porous nanowires (PNWs) with controllable composition are synthesized through an ultrasound-assisted galvanic replacement reaction. The porous structure, surface strain, and electronic property of PtCu PNWs are optimized by tuning composition, which can improve activity for ORR. Electrochemical tests reveal that the mass activity of Pt_0.5Cu_0.5 PNWs (Pt/Cu atomic ratio of 1:1) reaches 0.80 A mg_Pt^?1, which is about 5 times higher than that of the commercial Pt/C catalyst. Notably, the improved activity of the porous nanowire catalyst is also confirmed in the single-cell test. In addition, the large contact area with the carrier and internal interconnection structure of Pt_0.5Cu_0.5 PNWs enables them to exhibit much better durability than the commercial Pt/C catalyst and Pt_0.5Cu_0.5 nanotubes in accelerated durability test.