Mo_xW_1−x(S_ySe_1−y)₂ Alloy Nanoflakes for High‐Performance Electrocatalytic Hydrogen Evolution

Abstract

1wileyonlinelibrary.com www.particle-journal.com www. MaterialsViews.com Over years, layered transition metal dichalcogenides (TMDs) have shown vast potentials in catalyzing hydrogen evolution reaction (HER). While most current research works are exclusively focused on binary systems, very little attention has been paid to their ternary and quaternary alloys. In this work, a high-temperature solution method is employed to prepare 25 different Mo x W 1−x (S y Se 1−y ) 2 alloys with high yields. Resulting products are comprised of thin nanoflakes with cation and anion compositions independently tunable over the entire range. When evaluated as HER electrocatalysts in acids, these materials exhibit high activity and durability with small onset overpotentials and Tafel slopes. Furthermore, some general trend in their compositionactivity correlation is observed, and a few most active combinations successfully identified. This study may provide valuable insights in the future search of high-performance HER electrocatalysts based on TMDs.recently demonstrated a high-temperature solution method to prepare Mo(S x Se 1−x ) 2 alloy nanoflakes with monolayer or fewlayer thickness and fully tunable chemical composition. [18] It was evidenced that the incorporation of Se modified the d band electronic structure of Mo, and impacted its hydrogen adsorption free energy (ΔG H ). As a result, alloyed nanoflakes, especially with the chemical composition of MoSSe, were observed to have improved performance in comparison to either MoS 2 or MoSe 2 alone. [18] Encouraged by above progresses, we further propose that quaternary TMD alloys consisting of Mo, W, S, and Se may also hold unique promise for HER electrocatalysis. The compositional tunability on both cations and anions provides us two independent degrees of freedom to adjust the ΔG H , which, at the best scenario, may closely approach the thermoneutral, thus giving rise to optimal HER activity. Unfortunately, as far as we aware, there is no study available at present to explore quaternary TMD alloys for HER. To this end, in this work, we extend the high-temperature solution method developed by us earlier to the preparation of ternary or quaternary TMD alloys with a general formula of Mo x W 1−x (S y Se 1−y ) 2 . Their HER activities are systematically measured and compared in parallel. Through these experiments, we observe some general correlation between their electrocatalytic activity and chemical compositions, and identify a few most active combinations. Results and Discussion25 different alloy nanoflakes having a general formula of Mo x W 1−x (S y Se 1−y ) 2 (where x, y = 0, 0.33, 0.5, 0.67 or 1) were synthesized using an established high-temperature solution method by reacting the calculated amounts of MoCl 5 and/or WCl 6 with S and/or Se powders in a mixed solvent of oleylamine and 1-octadecene at 300 °C under N 2 atmosphere (see the Experimental for details). [16,18] Oleylamine was chosen as the solvent for its appreciable solubility toward both S and Se powders, forming...

Mo‐Doped Ni3S2 Nanowires as High‐Performance Electrocatalysts for Overall Water Splitting

“…The diffraction peaks at 21.8, 31.2, 37.9, 50 and 55.3 can be assigned to (100), (1‐10), (111), (210) and (2‐11) planes of Ni 3 S 2 , which are well indexed to the standard diffraction pattern of Ni 3 S 2 (JCPDS card no.73‐0698). After Mo doping, the peak at 31.2° slightly shift toward the low diffraction angle, possibly due to the fact that Mo is partially doped into the lattice of nickel sulfides, which is usually observed in other metal doping catalysts . In addition, a small peak located at 55.6° is also observed, which can be assigned to the NiMo 3 S 4 (JCPDS card no.…”

Interlayer Nanoarchitectonics of Two‐Dimensional Transition‐Metal Dichalcogenides Nanosheets for Energy Storage and Conversion Applications

“…[1][2][3][4][5] Owing to their high anisotropy and unique crystal structures, MX 2 can be utilized in a variety of energy conversion and storage applications, including water splitting cells, rechargeable batteries, supercapacitors, fuel cells, as well as various electronic and optoelectronic devices, etc. [6][7][8][9][10][11] Nanoengineering (morphology, size, number of layers, edges, defects), [12][13][14][15][16][17] phase conversion, [18][19][20][21][22][23] and composition tuning (alloying, doping with foreign transition metal), [24][25][26][27][28][29][30][31] represent the hot research areas in the recent past, aiming at modulation of the material properties and improvement of the device performances. Such impressive progress benefits from the success in synthesizing nanostructured MX 2 with precisely controlled parameters including edge density and crystalline phase.…”

Layered Ternary and Quaternary Transition Metal Chalcogenide Based Catalysts for Water Splitting

“…A thorough study of the composition compositional effects using Mo, W, S and Se was performed by Gong et al [139], where 25 different compositions were synthesized through a solution-phase method. The work identified WS 2 , Mo 0.67 W 0.33 S 2 , Mo 0.5 W 0.5 SSe and Mo 0.33 W 0.67 S 1.33 Se 0.67 as the best performing compositions and noted that in general the ternary or quaternary catalysts outperformed their binary counterparts.…”

“…The red color labels compositions with TOF > 0.1 s −1 ; the magenta color labels compositions with 0.06 < TOF < 0.1 s −1 ; the blue color labels compositions with 0.04 < TOF < 0.06 s −1 . Adapted with permission from Reference [139], copyright (2016), Wiley-VCH.…”