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Pseudocapacitors have attracted more and more attention during the recent years because of their high capacitance and large energy density. As a traditional pseudocapacitive material, WO3 possesses high theoretical capacitance and good conductivity among various transition metal oxides. Herein, a nanoflower-like WO3 (NFL-WO3) electrode with perfect electrochemical performance is synthesized through a facile and effective electrodeposition method. The NFL-WO3 electrode after optimization exhibits a very high areal specific capacitance (Ca) of 658 mF cm−2, which is the highest one in pure WO3 materials to the best of our knowledge and a large gravimetric specific capacitance (Cg) of 196 F g−1 at a scan rate of 10 mV s−1. Our result demonstrates the excellent balance between Ca and Cg compared with other reported WO3 based materials. After experiencing 5000 cycles, 85% of its capacitance can still be retained. Based on the full analysis of cyclic voltammetry curves and Nyquist plots, the pseudocapacitance should be the dominate contribution to the total capacitance. In addition, it can be assembled into an asymmetric supercapacitor for powering small electronics (light-emitting diode sets and mobile phone). All of the above exhibit the potential application of the NLF-WO3 electrode in energy storage devices. [ABSTRACT FROM AUTHOR]

Abstract: Pt nanoparticles were successfully deposited on ordered mesoporous carbons (CMK-3) using a pulse microwave-assisted polyol method. CMK-3 with three different pore sizes, obtained by using boric acid as the pore-expanding agent, were adopted. The pore size was controlled to be 4.4, 6.1, and 6.7nm while the highly ordered structure was still maintained. With these different CMK-3 samples as the support, the particle size of Pt was identical, about 2nm. It was found that the electrochemical surface area was almost the same in these three cases and the alcohol electrooxidation activity was not increased but decreased a little along with the pore size increment. The increased pore size of CMK-3 had no obviously positive effect on easier mass transfer and then a better electrocatalytic activity. This could be attributed to the very good 3-D interconnection of the nanospacings of CMK-3 per se. Moreover, combined with the theoretical calculation and confirmed by alternative current impedance results, the electrical conductivity of CMK-3 was dramatically decreased along with the pore size increasing, which counteracted the beneficial effect from easier mass transfer in the case of bigger pore size. Based on the present and reported results, it hints that when the carbon skeleton of carbon materials is different, the modification skills are changed for improving their structure in order to make them suitable for electrocatalysts supports. [Copyright &y& Elsevier]

Abstract: PtSn@Rh/C-HT catalysts were designed and synthesized by a two-step sequence synthesis: Rh was firstly deposited on the carbon support and then PtSn through microwave assisted polyol method, followed by the heat treatment (HT) in a reductive atmosphere. This well-designed process provided PtSn@Rh/C-HT with a desirable electrocatalytic activity towards the electrooxidation of ethanol as well as its intermediate products. Especially, for the acetic acid electrooxidation, PtSn@Rh/C-HT behaved quite different from Pt/C, PtSn/C, PtSn@Rh/C without heat-treatment, and PtSnRh/C fabricated through one-step method, without the characteristic peaks for hydrogen adsorption–desorption but significant oxidation current of acetic acid. This gives a platform for taking full advantage of the joint synergistic effect among Pt, Sn and Rh for direct ethanol fuel cell applications. [Copyright &y& Elsevier]

Abstract: In the present work, the activity of Pt x Sn y /C catalysts towards ethanol, acetaldehyde and acetic acid electrooxidation reactions is investigated for each one separately by means of cyclic voltammetry. To this purpose, a series of Pt x Sn y /C catalysts with different atomic ratio (x:y =2:1, 3:2, 1:1) and small particle size (∼3nm) are fast synthesized by using the pulse microwave assisted polyol method. The catalysts are well dispersed over the carbon support based on the physicochemical characterization by means of XRD and TEM. Concerning the ethanol electrooxidation, it is found that the Sn addition strongly enhances Pt''s electrocatalytic activity and the contributing effect of Sn depends on: (i) the Sn content and (ii) the operating temperature. More precisely, at lower temperatures, Sn-rich catalysts exhibit better ethanol electrooxidation performance while at higher temperatures Sn-poor catalysts give better performance. In the case of acetaldehyde electrooxidation, Pt1Sn1/C catalyst exhibits the highest activity at all the investigated temperatures; due to the role of Sn, which could effectively remove C2 species and inhibit the poison formation by supplying oxygen-containing species. Finally, it is found that the Pt x Sn y /C catalysts are almost inactive (little current was measured) towards the acetic acid electrooxidation. The above findings indicate that Sn cannot substantially promote the electrooxidation of acetic acid to C1 species. [Copyright &y& Elsevier]

Electrochemical two‐electron water oxidation reaction (2e− WOR) driven by renewable energy offers an attractive route to produce H2O2, while the corresponding electrocatalyst still requires further improvement for the activity, selectivity, and the resulting H2O2 yield. Surface‐interface engineering of electrocatalysts has great potential to advance 2e− WOR performance. This review provides a succinct yet comprehensive insight into the functional mechanisms of surface‐interfacial properties affecting 2e− WOR performance on electrocatalyst. The Gibbs free energy theoretical framework related to surface electronic structure and interfacial reactive kinetics mechanism related to electrolyte, electrode–electrolyte interface structure, and interfacial microenvironment properties are firstly discussed. Afterward, various surface‐interface engineering strategies toward high performance electrocatalysts including the regulation of surface electronic structure, the electrode–electrolyte interface structure, and the interfacial microenvironment have been overviewed. Rational manipulations of the above surface‐interfacial engineering strategies are critical to design highly efficient 2e− WOR electrocatalysts, leading to the development of the green H2O2 production. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER) plays an indispensable role in hydrogen economy. However, the development of highly active and durable Pt catalysts remains a great challenge. A homogenously‐dispersed, ultrafine and chemically anchored Pt‐based catalyst is successfully synthesized with the regulation of ‐SH groups tethered to SBA‐15 template. The ‐SH not only regulates the particle size of Pt, but also modifies the chemical environment of the carbon support by converting itself into heteroatom—S. The obtained catalyst (Pt/OMCSH) exhibits superior HER catalytic activity (15.4 mV at 10 mA cm−2; 28.4 mV dec−1; 1.0 M KOH) and stability to benchmark samples and most of the previously reported Pt‐based electrocatalysts. First‐principles calculations reveal that the presence of S in the carbon support regulates the electronic structure of Pt and strengthens the metal‐support interaction, thus boosting the reaction kinetics and enhancing the stability of Pt/OMCSH catalyst for HER. [ABSTRACT FROM AUTHOR]

In the present work, carbon supported PtMe (Me = Ir or Pd) electrocatalysts, with different atomic ratios (Pt/Me (20 wt%) = 3:1, 1:1, 1:3), are thoroughly investigated towards CO tolerance and durability, as anode and cathode for H 2 -PEMFCs (hydrogen fed proton exchange membrane fuel cells) application. The electrocatalysts are prepared via a pulse-microwave assisted polyol synthesis method and their durability and electrocatalytic activity in presence and absence of CO are evaluated using the techniques of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and rotating disk electrode (RDE). For the investigation of CO tolerance a protocol is set that could be used by other research groups, since various procedures are reported in literature. It is found that Pd/C shows higher CO tolerance than Pt/C, while the PtPd 3 /C exhibits the highest CO tolerance ability, even after being exposed for 9 h at 400 ppm CO. Despite the fact that Pt 3 Ir/C shows higher CO tolerance ability than Pt/C, it cannot resist at such high CO concentrations for more than 6 h. Finally, it is found that PtIr/C and PtPd/C exhibit very good durability even after 5000 accelerated durability test (ADT) cycles, while Pt 3 Pd/C and PtPd/C present the highest mass activities (339.4 and 410 mA/mg Pt respectively at 0.9 V), which are 4 and 5 times higher than the one observed over commercial Pt/C (82.75 mA/mg Pt). • PtMe (Me=Ir or Pd)/C are investigated towards CO-tolerance and ORR durability in acidic media. • The insertion of Pd improves Pt's tolerance, showing the optimum resistance at Pt : Pd=1 : 3. • Platinum alloys exhibit considerable improvement in both activity and durability towards ORR. • The addition of small amounts of Pd or Ir improves the electrocatalytic activity of pure platinum. • Both PtIr/C and PtPd/C exhibit good durability after 5000 accelerated durability test- cycles. [ABSTRACT FROM AUTHOR]

Owing to their exceptional properties, high‐entropy alloys (HEAs) have received considerable attention in the field of electrocatalysis. However, few studies focus on the origin of their outstanding performance. Here, carbon‐supported PtFeCoNiMn (with an atomic ratio of 21:20:20:20:19) HEA nanoparticles via shock‐heating and shock‐cooling strategy are rationally designed and successfully prepared. The above five metal elements are rationally selected from the perspective of thermodynamics and geometric effects. Subsequently, the alloying process of the PtFeCoNiMn HEA is investigated via operando X‐ray diffraction characterizations. The electronic structures of each metal atom on the PtFeCoNiMn HEA and monometallic nanoparticles surface are revealed by density function theory calculations for illustrating the performance enhancement mechanism. It is found that Pt atoms on the PtFeCoNiMn HEA surface exhibit a wider range of d‐band center distribution range than the corresponding monometallic nanoparticles, which contributes to the enhanced selective adsorption of O2 reactants/intermediates. Importantly, some Fe, Co, Ni, and Mn atoms on the HEA surface manifest less positive d‐band center values than the corresponding monometallic nanoparticles, with similar d‐band center positions to some Pt atoms. This indicates that the inactive atoms in monometallic nanoparticles can be transformed into ORR active sites in the HEA matrix owing to the electronic interaction between adjacent atoms. [ABSTRACT FROM AUTHOR]

While Pt‐based binary alloys hold promising potential as cathode catalysts in proton exchange membrane fuel cells (PEMFCs) due to their desirable properties compared with monometallic counterparts, their weak interactions with carbon support make them challenging for practical cell implementation. Here, the PtFe alloys are uniformly deposited onto the surface of Fe‐Nx‐enriched nanocubes (FeNC) via surface confinement and internal vapor phase etching. The combined action of PtFe alloy and FeNC support acts as the electronic structure modulator resulting in the optimized intermediate adsorption (revealed by density function theory calculations), thereby boosting intrinsic activity to oxygen reduction reaction (ORR) and simultaneously enhancing their interactions. The resultant Pt1Fe1 @ Fe0.5NC‐900 catalyst with a low Pt loading (0.065 mgPt cm−2) exhibits excellent mass activity and stability toward ORR in acidic media. When incorporated into a PEMFC, it delivers a superior peak power density of 1.05 W cm−2 and satisfactory stability performance. [ABSTRACT FROM AUTHOR]