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2. Interfacial Electron Coupling in Au Nanoparticle/CoFe Layered Double Hydroxide Nanosheet Heterostructures as Water Oxidation Catalysts.

Author

Sui, Mingchong, Wang, Fangqing, Liu, Caichi, Hao, Qiuyan, Li, Ying, Liu, Hui, and Liang, Limin

Abstract

Cobalt–iron layered double hydroxide (CoFe LDH) is considered an advanced electrocatalyst toward the alkaline oxygen evolution reaction (OER), yet its poor stability is still a huge challenge. Here, based on an innovative spontaneous redox reaction (SRR) method, we synthesize a gold-nanoparticle-decorated CoFe LDH heterostructure on nickel foam (Au/CoFe LDH/NF) at room temperature. The heterostructure catalyst not only exhibits a low overpotential of 233 mV at 10 mA cm–2 but also displays 400 h stability without any degradation at ∼200 mA cm–2. The experimental and density functional theory (DFT) calculations validate that Au/CoFe LDH/NF with strong electronic coupling at the interface optimizes the electronic structure, reducing the OER energy barrier. In situ Raman spectra demonstrate that the transfer of electrons from Au nanoparticles to CoFe LDH alleviates the structural distortion of the catalyst during the OER, which is responsible for the strengthened stability. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Mo-Doped Ni3S2 Nanosheet Arrays for Overall Water Splitting.

Author

Gao, Yaohui, He, Wenjun, Cao, Da, Wang, Fangqing, Li, Ying, Hao, Qiuyan, Liu, Caichi, and Liu, Hui

Abstract

Designing effective and low-cost bifunctional electrocatalysts for the alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential to achieve green development of the hydrogen economy. Herein, we have developed Mo-doped Ni3S2 nanosheet array catalysts with excellent electrochemical properties. Only 85 mV (HER) and 230 mV (OER) overpotentials are required under alkaline conditions at 10 mA cm–2 and remain undegraded for 100 h. In addition, it only required 1.52 V at 10 mA cm–2 in an alkaline electrolyzer, and it remained unchanged for more than 100 h in stability tests, outperforming most reported electrocatalysts. Experiments and density functional theory (DFT) calculations confirmed that the doping of Mo could expose more active sites of Ni3S2 and optimize the adsorption free energy of the intermediate, which in turn improves its intrinsic activity. This work reveals the key role of Mo in Ni3S2 electrocatalytic performance enhancement at the atomic scale. [ABSTRACT FROM AUTHOR]

Published
2023
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28. Engineering Selenium Vacancies on CoSe2 Nanoarrays for Alkaline Hydrogen Evolution.

Author

Pan, Xiaowei, He, Wenjun, Cao, Da, Li, Ying, Liu, Caichi, Liang, Limin, Hao, Qiuyan, and Liu, Hui

Abstract

The development of highly efficient nonnoble metals toward hydrogen evolution reaction (HER) electrocatalysts is significant for producing hydrogen via water electrolysis. Selenides are becoming increasingly attractive owing to their excellent HER activity. Herein, CoSe2 nanorods were successfully manufactured on a carbon cloth (CC) and selenium vacancies were obtained using a plasma cleaner (CoSe2-VSe/CC) to enhance their intrinsic catalytic activity. The synthetic catalyst exhibited a lower overpotential of 88 mV at 10 mA cm–2 in 1 M KOH and high durability over 100 h at 100 mA cm–2, which can be ascribed to the increased electrochemical surface area and rapid electron transfer. In addition, density functional theory (DFT) calculations showed that introducing Se vacancies optimized the hydrogen adsorption energy on the Se site and reduced the transition-state energy barrier of water dissociation. This study laid a firm foundation for preparing high-performance and stable electrocatalysts via anion defect engineering. [ABSTRACT FROM AUTHOR]

Published
2023
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33. Influence of Rapid Thermal Annealing on the Characteristics of InGaN/GaN MQWs

Author

Tian Yuan, Liang Limin, Xie Xinjian, Liu Hui, Hao Qiuyan, and Liu Caichi

Subjects
InGaN/GaN MQWs, RTA, XRD, PL spectrum, Engineering (General). Civil engineering (General), TA1-2040
Abstract

N-type InGaN/GaN multiple-quantum-wells (MQWs) were grown on sapphire substrates by metal organic chemical vapor deposition (MOCVD). The crystal quality and optical properties of samples after rapid thermal annealing (RTA) at different temperatures in a range from 400 to 800°C are investigated by X-ray diffraction (XRD) and photoluminescence (PL) spectrum. The experimental results show that the peaks of InGaN, InN and In can be observed in all samples. And the results are induced by the phase separation and In-clusters. The luminescence peak of the samples annealed showed a red shift. It is caused by strain stress relaxation during the RTA process. Furthermore, some defects can be eliminated and the best annealing temperature is from 500°C to 700°C.

Published
2016
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