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Water splitting has been widely considered to be an efficient way to generate sustainable and renewable energy resources in fuel cells, metal–air batteries and other energy conversion devices. Exploring efficient electrocatalysts to expedite the anodic oxygen evolution reaction (OER) is a crucial task that needs to be addressed in order to boost the practical application of water splitting. Intensive efforts have been devoted to develop mixed transition metal based chalcogenides as effective OER electrocatalysts. Herein, we have reported synthesis of a series of mixed metal selenides containing Co, Ni and Cu employing combinatorial electrodeposition, and systematically investigated how the transition metal doping affects the OER catalytic activity in alkaline medium. Energy dispersive spectroscopy (EDS) was performed to detect the elemental compositions and confirm the feasibility of compositional control of 66 metal selenide thin films. It was observed that the OER catalytic activity is sensitive to the concentration of Cu in the catalysts, and the catalyst activity tended to increase with increasing Cu concentration. However, increasing the Cu concentration beyond a certain limit led to decrease in catalytic efficiency, and copper selenide by itself, although catalytically active, showed higher onset potential and overpotential for OER compared to the ternary and quaternary mixed metal selenides. Interestingly, the best quaternary composition (Co 0.21 Ni 0.25 Cu 0.54 ) 3 Se 2 showed similar crystal structure as its parent compound of Cu 3 Se 2 with slight decrease in lattice spacings of (101) and (210) lattice planes (0.0222 Å and 0.0148 Å, respectively) evident from the powder X-ray diffraction pattern. (Co 0.21 Ni 0.25 Cu 0.54 ) 3 Se 2 thin film exhibited excellent OER catalytic activity and required an overpotential of 272 mV to reach a current density of 10 mA cm −2 , which is 54 mV lower than Cu 3 Se 2 , indicating a synergistic effect of transition metal doping in enhancing catalytic activity.
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Modulation of electrocatalytic activity by tuning anion electronegativity: case study with copper chalcogenides
Abstract Anion-tuning in metallic chalcogenides has been shown to have a significant impact on their electrocatalytic ability for overall water splitting. In this article, copper-based chalcogenides (Cu2X, X= O, S, Se, and Te) have been systematically studied to examine the effect of decreasing anion electronegativity and increasing covalency on the electrocatalytic performance. Among the copper chalcogenides, Cu2Te has the highest oxygen evolution reaction (OER) activity and can sustain high current density of 10 and 50 mA cm−2for 12 h. The difference in intrinsic catalytic activity of these chalcogenide surfaces have been also probed through density functional theory calculations, which was used to estimate energy of the catalyst activation step. It was observed that the hydroxyl adsorption on the surface catalytic site is critically important for the onset and progress of OER activity. Consequently, it was also observed that the –OH adsorption energy can be used as a simple but accurate descriptor to explain the catalytic efficiency through volcano-like correlation plot. Such observation will have a significant impact on developing design principle for optimal catalytic surface exhibiting high performance as well as prolonged stability.
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- Award ID(s):
- 2155175
- PAR ID:
- 10471731
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Journal of Physics: Energy
- Volume:
- 5
- Issue:
- 4
- ISSN:
- 2515-7655
- Format(s):
- Medium: X Size: Article No. 045016
- Size(s):
- Article No. 045016
- Sponsoring Org:
- National Science Foundation
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