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Raw Materials and Moisturizing Properties of Yunnan Jianshui Purple Pottery in China
Journal of Ceramics 2023, 44(1): 95-103
Published: 01 February 2023
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Pottery has a long history with various types of ware shapes, which constitutes an important part of Chinese culture. As one of the four famous types of pottery in China, Jianshui purple pottery has unique craftsmanship and artistic characteristics. Although purple pottery has already been widely used in tea storage and steam boilers, many characteristics of purple pottery are based on experience and legend, lacking the support of experience data. The relationship between the clay and the properties of the purple pottery is still unknown. Thus, the responses to temperature and humidity change under different environments were systematically studied. The raw materials, mud and finished products of Jianshui purple pottery, together with their phase, particle size and structure, were also studied by using XRD, SEM, TG-DSC and Mercury Porosimeter. It is found that Jianshui purple pottery’s small clay particle size resulted in its low porosity of the finished product. As a result, it has a good moisturizing property, which meets the requirement of long term storage of the tea that requires post fermentation. The relationships among the clay particle size, composition and porosity of the finished product, as well as the humidity maintenance properties, are discussed.

Open Access Research Article Issue
MOF-Derived Iron-Cobalt Phosphide Nanoframe as Bifunctional Electrocatalysts for Overall Water Splitting
Energy & Environmental Materials 2024, 7(6)
Published: 23 February 2024
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Transition metal phosphides (TMPs) have emerged as an alternative to precious metals as efficient and low-cost catalysts for water electrolysis. Elemental doping and morphology control are effective approaches to further improve the performance of TMPs. Herein, Fe-doped CoP nanoframes (Fe-CoP NFs) with specific open cage configuration were designed and synthesized. The unique nano-framework structured Fe-CoP material shows overpotentials of only 255 and 122 mV at 10 mA cm−2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, overwhelming most transition metal phosphides. For overall water splitting, the cell voltage is 1.65 V for Fe-CoP NFs at a current density of 10 mA cm−2, much superior to what is observed for the classical nanocubic structures. Fe-CoP NFs show no activity degradation up to 100 h which contrasts sharply with the rapidly decaying performance of noble metal catalyst reference. The superior electrocatalytic performance of Fe-CoP NFs due to abundant accessible active sites, reduced kinetic energy barrier, and preferable *O-containing intermediate adsorption is demonstrated through experimental observations and theoretical calculations. Our findings could provide a potential method for the preparation of multifunctional material with hollow structures and offer more hopeful prospects for obtaining efficient earth-abundant catalysts for water splitting.

Research Article Issue
Co2P/CoP heterostructures with significantly enhanced performance in electrocatalytic hydrogen evolution reaction: Synthesis and electron redistribution mechanism
Nano Research 2023, 16(11): 12830-12839
Published: 31 October 2023
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Heterostructures are often constructed to modulate the electronic states of the two catalysts, achieving high-performance in alkaline hydrogen evolution reaction (HER). Various mechanisms have been proposed for the heterostructural catalysts, which however awaits further approvement. Herein, a heterostructure composed of Co2P and CoP was successfully prepared with significantly enhanced HER catalytic activity relative to the endmembers. The ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) revealed the effective promotion of the self-driven transferring of electrons from CoP to Co2P and the accumulation of electrons on the P sites in Co2P due to the strong electronic coupling of built-in electric field in the Co2P/CoP interface. In situ electrochemical impedance spectroscopy (EIS) and poison experiments confirmed the Heyrovsky step of H* intermediate depleting on electronegative P sites and contributions of both metal and P to the reactivity in the Co2P/CoP. Density functional theory (DFT) calculations clarify that the electronic structure at interface of the heterojunction significantly weakens the hydrogen adsorption free energy (ΔGH* ads) of P site in Co2P/CoP to near zero. We also propose an electronic redistribution strategy for heterostructures that activates the multiple routes mechanism and production of more active sites. The working mechanism is expected to be further extended to other transition metal compounds for efficient HER activity.

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