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Water electrolysis is currently a major technique to produce clean hydrogen, which is regarded as a promising and sustainable energy carrier. The efficiency of water electrolysis is highly dependent on the oxygen evolution reaction (OER) on the anode. The evaluation of an OER electrocatalyst is frequently carried out on a three-electrode system in a container of electrolyte. Herein, we found that the electrode positions in the electrolyte container could significantly affect the data acquisition of OER performance. After a detailed investigation, we reveal that the difference of the OER activity of an electrocatalyst at a different position is originated from their different iRu drop and the gas diffusion resistance. For the first time, this work evokes concerns on the accurate evaluation of electrocatalysts regarding the electrode position. For fair comparisons and reliable results, it is strongly suggested to keep the electrode position unchanged in the electrochemical measurements. In addition, the establishment of a standard electrolyzer setup for electrocatalysis evaluation in the electrochemical community is also called for. [ABSTRACT FROM AUTHOR]

Herein we demonstrate a surface engineering strategy, namely, decorating Au on the surface of bimetallic PtFe nanocatalysts, to effectively decrease the adsorption energy of CO on the Pt center, which promotes the electrocatalytic activity towards methanol oxidation, far better than those of PtFe and commercial Pt/C catalysts. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are a family of high-profile layer materials with tunable metal species and interlayer spacing, and herein the LDHs are first investigated as bifunctional electrocatalysts. It is found that trinary LDH containing nickel, cobalt, and iron (NiCoFe-LDH) shows a reasonable bifunctional performance, while exploiting a preoxidation treatment can significantly enhance both oxygen reduction reaction and oxygen evolution reaction activity. This phenomenon is attributed to the partial conversion of Co2+ to Co3+ state in the preoxidation step, which stimulates the charge transfer to the catalyst surface. The practical application of the optimized material is demonstrated with a small potential hysteresis (800 mV for a reversible current density of 20 mA cm−2) as well as a high stability, exceeding the performances of noble metal catalysts (commercial Pt/C and Ir/C). The combination of the electrochemical metrics and the facile and cost-effective synthesis endows the trinary LDH as a promising bifunctional catalyst for a variety of applications, such as next-generation regenerative fuel cells or metal-air batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heterogenous electrocatalytic epoxidation of cyclooctene directly using water as oxygen source was achieved. • Co 4 P 2 W 18 shows higher Faradic efficiency (∼36 %) for epoxide than CoPW 11 and other typical electrocatalysts. • The O atom directly transfer from water to adsorbed cyclooctene on the surface of Co 4 P 2 W 18. • The adjacent terminal O to Co site plays key role in adsorption and activation of water and cyclooctene. The electrocatalytic epoxidation directly using water as oxygen source is considered as a sustainable strategy to achieve epoxide production under ambient conditions. However, it is challenging to develop non-noble metal based heterogeneous electrocatalysts for efficient epoxidation with a deep understanding of the structure–activity relationships. In this work, we report a Weakley-polyoxometalate Na 10 [Co 4 (H 2 O) 2 (PW 9 O 34) 2 ] (Co 4 P 2 W 18) with high efficiency toward electrocatalytic epoxidation of cyclooctene via directly transfer oxygen atom from water. A significantly higher faradaic efficiency of cyclooctene oxide was achieved over Co 4 P 2 W 18 than a Keggin type Co substituted polyoxometalate Na 5 [Co(H 2 O)PW 11 O 39 ] (CoPW 11) and some other typical electrocatalysts including RuO 2 , IrO 2 , and Co 3 O 4 in our system. Experimental results and theoretical calculation indicate that the oxygen atom directly transfers from water for the epoxidation of cyclooctene via the cleavage of O−H of pre-adsorbed water as the rate-determined step. Further calculation demonstrates that the water and cyclooctene were adsorbed by Co site and their adjacent terminal oxygen atom during the epoxidation reaction. With the assistance of this terminal oxygen atom for adsorption and as an electron capture center, lower energy barriers for activation of water and cyclooctene are observed on Co 4 P 2 W 18 than on CoPW 11. Our study provides atomic insight into how structure affects catalytic activity, which benefits designing efficient electrocatalysts. [ABSTRACT FROM AUTHOR]