Li Mengmeng,Huang Shuang,Zhang Hang,Wang Lei,Zhong Shengliang
Background: Researchers have pursued the new synthesis method. As a newly developed method, microwave (MW), ultrasound (US) and ultraviolet light (UV) assisted synthesis has drawn increasing interests. Under the synergistic effect, many materials with new structure, morphology and properties
may be found. As an important rare-earth phosphate, DyPO4 was selected and the effect of MW, US and UV on the preparation was investigated. Methods: The DyPO4·1.5H2O nanostructures were prepared by MW, US, UV and their combination. Results: Hexagonal DyPO4·1.5H2O
microcrystals obtained under MW irradiation were broomstick bundles. Needle-shaped products were formed in the presence of MW and US. Interestingly, the broom-sheaf-like structures can self-assemble into flower-shaped structures upon the irradiation of MW and UV. Whereas, MW/UV/US synergetic
heating results in mixed morphologies of flower-like and needle-shaped structures. Conclusion: The growth of DyPO4 nanostructures can be tuned by selecting the combination of heating method of MW, US and UV.
The hydrophilic property of the catalytic interface has been seldom focused on particularly, although many green and sustainable catalysis transformations involve water. Addressing the issue, we prepared Dy–Ni–P catalysts for the 5-hydroxymethylfurfural oxidation reaction (HMFOR) to 2,5-furandicarboxylic acid (2,5-FDCA) in this work. The catalysts were clarified as (DyPO4)m/Ni2P composites with molar ratio m within 0.08–0.28 by ICP-OES, XRD, XPS, and HRTEM characterizations. The catalytic performance of samples was comprehensively analyzed by the HPLC technique, 1H NMR spectra, and various electrochemical tests, indicating that the introduction of DyPO4 in a proper amount (m = 0.16) would significantly enhance the catalytic efficiency versus singular Ni2P in terms of 2,5-FDCA yield (91 vs 26%), selectivity (99 vs 47%), and Faradaic Efficiency (F.E.: 98 vs 70%). The enhancements were accompanied by improved kinetic features such as the Tafel slope (53 vs 95 mV dec–1) and intrinsic activity (3.3 vs 1.7 mA cm–2). The boosting endowment (DyPO4)m/Ni2P stands among the top members of reported Ni-based HMFOR catalysts. The promoter effect of DyPO4 was further investigated by H2O-TPD, contact angle, zeta potential, OCP, and EIS measurements. It was testified that the nonhydrophilic Ni2P surface would be converted to a hydrophilic composite interface with the introduction of DyPO4; in line with the essential change, transfer of reactants and activation of water were obviously intensified with the lowered charge transfer resistance along the catalytic interface, which was responsible for the enhanced catalytic behavior of (DyPO4)m/Ni2P versus Ni2P. The above discovery made the topic regarding water indicate that the hydrophilic property of the catalytic interface played a significant role in facilitating heterogeneous catalysis transformations involving water; exampled by the current (DyPO4)m/Ni2P for HMFOR, rare-earth phosphate could be referred to as an outstanding hydrophilic promoter to innovate excellent catalysts for technology-important chemical engineering involving water.
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