A small amount of ruthenium (Ru) was introduced into binary CoSe 2 /C through chemical reduction to obtain ternary Ru(CoSe 2 )/C. The effects of heat-treatment (HT) on crystal structures and electrocatalytic activities toward oxygen reduction reaction (ORR) of binary and ternary catalysts were investigated. Upon the heat-treatment at 400 • C, a simple phase transformation from orthorhombic to cubic CoSe 2 took place in the absence of Ru, resulting in larger crystallite size and poorer ORR activity of CoSe 2 /C-HT. However, with the incorporation of Ru, a new cubic (Ru x Co y )Se 2 like phase might be formed as the Ru could enter the CoSe 2 lattice during the phase transformation, which not only prevented the grain growth and stabilized the structure, but also provided the new efficient ORR active site. Ultimately, high activity and excellent stability were achieved for Ru(CoSe 2 )/C-HT with the synergy of Ru with Co and Se, which significantly enhanced Ru utilization. The open circuit potential and maximum power density reached 0.87 V and 151 mW • cm −2 in the H 2 /O 2 single cell test, respectively, which were 24.3% and 242.5 times larger than those of CoSe 2 /C-HT (0.70 V and 0.62 mW • cm −2 ), respectively. The normalized degradation was 2.2% after 1000 cycles during the accelerated degradation test.

Carbon supported cobalt nickel selenide (Co,Ni) Se2/C ternary catalysts were prepared by a simple microwave‐assisted polyol method. The effects of the Co amount (x), in terms of the Co content over the total amounts of Co and Ni presented in (CoxNi1‐x) Se2/C (x=0, 0.25, 0.33, 0.50, 0.67, 0.75 and 1.0), on the crystal structures, surface morphologies, microstructures, electrocatalytic activities and stabilities toward oxygen reduction reaction (ORR) were systematically investigated. It was found that the incorporation of Co into NiSe2/C apparently reduced the average crystallite sizes of the as‐prepared (CoxNi1‐x) Se2/C (00.5), in particular, with (Co0.75Ni0.25) Se2/C which showed no loss in EORR after 1000 cycles. The excessive amount of Co introduced into NiSe2/C resulted in the coexistence of a cubic (CoxNi1‐x) Se2 single crystallite and an orthogonal CoSe2 polycrystallite, which might be beneficial to inhibit the grain growth and to provide more active sites. Furthermore, the formation of (CoxNi1‐x) Se2 might provide more stable structure for the ternary (Co0.75Ni0.25) Se2/C to impede the Se oxidation.

Carbon supported ruthenium tellurium (RuTe 2 /C) catalysts were synthesized with various Ru/Te ratios ( 2:1, 1.5:1, 1:1, 1:2, and 1:3) via a microwave route followed by heat-treatment. Effects of Ru/Te ratio on crystal structures, microstructures, chemical states and electrocatalytic activities toward oxygen reduction reaction (ORR) of RuTe 2 /C were systematically investigated. A mixed phase with predominant orthorhombic RuTe 2 and minor hexagonal Ru was identified. A novel synergistic effect was provided by RuTe 2 and Ru which acted as dual ORR active sites. The average particle sizes ranged 5.0 ∼ 8.4 nm, while the half-wave potentials (E 1/2 ) varied 0.57 ∼ 0.61 V in HClO 4 and 0.70 ∼ 0.72 V in KOH as the Ru/Te ratios changed from 2:1 to 1:3. The largest E 1/2 values of 0.61 V and 0.72 V, as well as the E 1/2 losses of 0.83% and 0.69% upon 1000 cycles or 3.28% and 0.97% (containing 2 mol • L −1 methanol) were obtained for the RuTe 2 /C (Ru/Te = 1:1) in HClO 4 and KOH, respectively, showing the best ORR activity and excellent stability with high methanol tolerance in both acidic and alkaline media. The preliminary cell performance revealed the maximum power density of 269 mW • cm −2 with impressive durability.

The carbon supported ruthenium tellurium (RuTe2/C) nanoparticles were prepared through a simple microwave polyol method and heat treatment at 350 ℃. Effects of Ru/Te molar ratio on the crystal structure, surface morphology, microstructure, electrocatalytic activity and stability, as well as methanol tolerance in an alkaline solution, were systematically investigated. The orthorhombic RuTe2 and hexagonal Ru were identified as the main phases. The catalyst nanoparticles were uniformly dispersed on the carbon support and the average particle size ranged 5.08.6 nm. The RuTe2/C catalyst prepared with Ru/Te=1:1 exhibited the best activity toward oxygen reduction reaction. The half-wave potential (E1/2) of 0.74 V with the electron transfer number of 3.7 was achieved in 0.1 mol•L -1 KOH solution. The E1/2 values decreased by 7 mV after 1000 potential cycles test in 0.1 mol•L -1 KOH, while remained unchanged in 0.1 mol•L -1 KOH containing 2 mol•L -1 methanol solutions, suggesting the excellent stability and methanol tolerance.

The carbon supported PdCu alloyed catalysts (PdCu/C) with different molar ratios of Cu to Pd (Cu/Pd), namely, Cu/Pd=2.0, 3.0, 4.0, and 5.0, were synthesized by a simple and facile two-step method. The Cu nanoparticles were first obtained by microwave assisted method, and then followed by galvanic substitution of Pd on Cu nanoparticles. The PdCu/C catalysts exhibited mainly cubic phase with the average crystallite sizes ranging 4.0~4.5 nm by varying the Cu/Pd ratios of 2.0~5.0. The microstructure and the activity toward oxygen reduction reaction (ORR) of PdCu/C were significantly influenced by the Cu/Pd ratios. The higher degree of alloying and better ORR activity could be achieved with the Cu/Pd=4.0. The half-wave potential (E 1/2 ) reached 0.760 V in the acid medium, which was only 40 mV lower than that of commercial Pt/C. Only 20 mV (2.6%) decrease in E 1/2 after 1000 cycles between 0.4 and 1.0 V suggested the good stability.

The Cover Feature shows that the synergy between Co and Ni resulting from microwave‐prepared (Co,Ni)Se2/C ternary catalysts enhances the electrocatalytic activity toward the oxygen reduction reaction. More information can be found in the Article by X. Cheng and co‐workers on page 2019 in Issue 14, 2018 (DOI: 10.1002/celc.201800190).

The ruthenium (Ru) precursor was introduced into carbon supported cobalt selenide (CoSe 2 /C) nanoparticles, which were prepared via a simple microwave route, to obtain the ternary carbon supported ruthenium cobalt selenide (RuCoSe/C) nanoparticles by chemical reduction of Ru on the CoSe 2 /C surface. Upon the subsequent heat treatment of RuCoSe/C at 400 ℃, a small amount of Ru introduced substituted some Co sites in the CoSe 2 through the phase transformation of orthorhombic to cubic CoSe 2 , which led to the formation of a new cubic phase of (Ru x Co 1-x )Se 2 /C. The half-wave and onset potentials were 0.68 V and 0.88 V (vs. RHE), respectively, in 0.1 molL -1 perchloric acid (HClO 4 ) solutions. The mass activity was as high as 0.09 mAg -1 Ru at 0.75 V, which is comparable to that of the commercial Pt/C (0.10 mAg -1 Pt). Only 15 mV loss in the half-wave potential was observed after 1000 cycles in 0.1 molL -1 HClO 4 , suggesting the efficient Ru utilization and excellent electrocatalytic stability.