Yin-chuan Wang,Zi-chen Wang,Gui-yong Xiao,Wei-li Xu,Kai Wang,Yan Jiao,Mei-li Qi,Yu-peng Lu
An oleic acid-assisted solvothermal method has been utilized to prepare hydroxyapatite (HA) nanofibers with a high flexibility and aspect ratio. Understanding the role of oleic acid in the synthesis of HA may provide effective routes for the design of advanced biomaterials. The concentration of OH− ions ([OH−]) has a great impact on the reaction system, which in turn affects the nucleation and crystal growth of HA. In this work, the effect of oleic acid on the morphology and structure of the as-prepared products under different concentrations of NaOH was investigated by XRD, FTIR and FE-SEM. The formation process of HA was also explored to better explain the role of oleic acid based on structured characteristics and morphology evolution. These results showed that oleic acid molecules absorbed on the surface of HA would effectively induce a one-dimensional crystal growth, even if the crystal growth habit had been changed under different [OH−]. For [OH−] < 1.50 M, [OH−]-responsive oleic acid and its corresponding behavior as a pH buffer can regulate pH at a relatively constant value. Besides, the flexible ultralong HA nanofibers can be formed at [OH−] = 1.25–1.50 M, while the crystallite size and preferred growth along the c-axis were both improved with an increase in [OH−] added.
Single-atom catalysts have been extensively researched in electrocatalytic oxygen reduction and evolution reactions (ORR/OER) due to their tunable coordination environment. However, the linear scaling relationship (LSR) of oxygen intermediate adsorption energies imposes limitations in simultaneously enhancing ORR/OER. Herein, a unique asymmetrically coordinated FeN 3 P 1 single-atom configuration coupled by Fe 2 P nanoparticle is synthesized via a prefabricated Fe-N/P coordination strategy. The accentuated structural distortion induced by Fe 2 P can effectively break the LSR, lowering the energy barriers for ORR/OER. Kinetically, a modulation of OH − concentration by Fe 2 P on the catalytic interface was identified by finite element simulation and molecular dynamics simulation, which can positively facilitate ORR/OER kinetics. The obtained Fe 2 P@FeN 3 P 1 -NC catalyst exhibits excellent bifunctional ORR/OER (∆E = 0.65 V) and a promising application in zinc-air battery. This work provides a valuable insight into simultaneous regulation of thermodynamic and kinetic behavior by tailored structure distortion and enriched surface ions for ORR/OER.
危险品化学品经营许可证（带存储）