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1,043 results on '"Liu, Xianhu"'

25. Active Phase on SrCo1–x Fe x O3−δ (0 ≤ x ≤ 0.5) Perovskite for Water Oxidation: Reconstructed Surface versus Remaining Bulk

Author

Li, Haiyan, Chen, Yubo, Ge, Jingjie, Liu, Xianhu, Fisher, Adrian C, Sherburne, Matthew P, Ager, Joel W, and Xu, Zhichuan J

Subjects
Chemical Sciences, Physical Chemistry, surface reconstruction, oxygen evolution, perovskite, oxides, cobalt, iron, CSD-46-All CSGB, Chemical sciences
Abstract

Perovskite oxides based on earth-abundant transition metals have been extensively explored as promising oxygen evolution reaction (OER) catalysts in alkaline media. The (electro)chemically induced transformation of their initially crystalline surface into an amorphous state has been reported for a few highly active perovskite catalysts. However, little knowledge is available to distinguish the contribution of the amorphized surface from that of the remaining bulk toward the OER. In this work, we utilize the promoting effects of two types of Fe modification, i.e., bulk Fe dopant and Fe ions absorbed from the electrolyte, on the OER activity of SrCoO3-δ model perovskite to identify the active phase. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the surface amorphization of SrCoO3-δ as well as SrCo0.8Fe0.2O3-δ after potential cycling in Fe-free KOH solution. By further cycling in Fe-spiked electrolyte, Fe was incorporated into the amorphized surface of SrCoO3-δ (SrCoO3-δ + Fe3+), yielding approximately sixfold increase in activity. Despite the difference in remaining perovskites, SrCoO3-δ + Fe3+ and SrCo0.8Fe0.2O3-δ exhibited remarkably similar activity. These results reflect that the in situ developed surface species are directly responsible for the measured OER activity, whereas the remaining bulk phases have little impact.

Published
2021

26. Active Phase on SrCo1-x Fe x O3-δ (0 ≤ x ≤ 0.5) Perovskite for Water Oxidation: Reconstructed Surface versus Remaining Bulk.

Author

Li, Haiyan, Chen, Yubo, Ge, Jingjie, Liu, Xianhu, Fisher, Adrian C, Sherburne, Matthew P, Ager, Joel W, and Xu, Zhichuan J

Abstract

Perovskite oxides based on earth-abundant transition metals have been extensively explored as promising oxygen evolution reaction (OER) catalysts in alkaline media. The (electro)chemically induced transformation of their initially crystalline surface into an amorphous state has been reported for a few highly active perovskite catalysts. However, little knowledge is available to distinguish the contribution of the amorphized surface from that of the remaining bulk toward the OER. In this work, we utilize the promoting effects of two types of Fe modification, i.e., bulk Fe dopant and Fe ions absorbed from the electrolyte, on the OER activity of SrCoO3-δ model perovskite to identify the active phase. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the surface amorphization of SrCoO3-δ as well as SrCo0.8Fe0.2O3-δ after potential cycling in Fe-free KOH solution. By further cycling in Fe-spiked electrolyte, Fe was incorporated into the amorphized surface of SrCoO3-δ (SrCoO3-δ + Fe3+), yielding approximately sixfold increase in activity. Despite the difference in remaining perovskites, SrCoO3-δ + Fe3+ and SrCo0.8Fe0.2O3-δ exhibited remarkably similar activity. These results reflect that the in situ developed surface species are directly responsible for the measured OER activity, whereas the remaining bulk phases have little impact.

Published
2021

49. Polyvinyl alcohol/boron nitride aerogels for radiative cooling.

Author

Xu, Yazhou, Zhang, Jingna, Wang, Jingjing, Zhu, Huijie, Zhang, Shixun, Pan, Yamin, Liu, Xianhu, Liu, Chuntai, and Shen, Changyu

Subjects
POLYVINYL alcohol, AEROGELS, NITRIDES, SUNSHINE, EMISSIVITY
Abstract

Daytime radiative cooling material provides a low‐energy way of cooling because it can reflect sunlight and radiate heat without consuming any energy. However, there are still great difficulties in manufacturing low‐cost, high‐efficiency, sustainable, and biodegradable daytime radiative cooling materials. In this paper, poly (vinyl alcohol)/boron nitride (PVA/BN) composite aerogels were prepared by freeze‐drying technology. By adjusting the PVA concentration and BN content, the aerogel can achieve high sunlight reflectivity (96%), high mid‐infrared emissivity (96%) and good thermal insulation performance. Therefore, the temperature of the aerogel can be reduced to 12.5°C lower than the ambient temperature at night, and 5.5°C lower than the ambient temperature under the direct sunlight of 900 W/m2. This aerogel opens an environmentally sustainable pathway for radiative cooling applications. [ABSTRACT FROM AUTHOR]

Published
2024
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50. Thermoplastic‐Polyurethane‐Based Foams via Water‐Assisted Thermally Induced Phase Separation for Daytime Passive Radiation Cooling.

Author

Wang, Lei, Yuan, Hongyue, Wang, Yi, Hou, Yangzhe, and Liu, Xianhu

Subjects
PHASE separation, POLYMER fractionation, DEIONIZATION of water, POROSITY, GLOBAL warming, FOAM
Abstract

In recent years, global warming has been increasing, while conventional cooling devices remain inefficient and can emit greenhouse gases. The research and development of passive daytime radiative cooling (PDRC) are of utmost importance. Herein, a novel technique called water‐assisted thermally induced phase separation (WA‐TIPS) is employed to prepare thermoplastic polyurethane (TPU) foams with a hierarchical micro/nanostructure. By adding 2 mL of deionized water, the TPU foam achieves a solar reflectance of up to 95.5% and can provide a cooling effect of up to 7 °C during daytime, showcasing its significant potential for PDRC applications. Furthermore, leveraging the WA‐TIPS technique, the cooling performance of a composite foam consisting of TPU and SiO2 nanoparticles is investigated. Remarkably, it is discovered that incorporating just 0.1 g of SiO2 nanoparticles allows the composite foam to achieve daytime cooling of up to 15 °C. In this work, not only a novel approach for constructing micro/nanostructures is introduced but also a theoretical and experimental framework for advancing the development of polymer or polymer composite PDRC devices is established. [ABSTRACT FROM AUTHOR]

Published
2024
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