Teng Li,Ruizi Wang,Xixi Wu,Wenzhe Liu,Zikang Cai,Jiwei Song,Chunyan Cao,Liangjie Yuan
Increasing interest in LiCoO 2 as a cathode material for Li-ion batteries has recently arisen due to its high operating voltage, high energy density and long cycle life. However, irreversible structural damage and severe side reactions at high cut-off voltages severely deteriorate the electrochemical performance of LiCoO 2 materials, resulting in a series of safety issues when used in batteries. In this work, PrPO 4 , Li 2 CO 3 and Co 3 O 4 are mixed and then treated at a high temperature to obtain PrPO 4 -modified LiCoO 2 with improved electrochemical performance at 4.55 V. XRD and Rietveld refinement results confirm that the modified LiCoO 2 materials exhibit well-ordered structures with compact unit cells. PrPO 4 is not incorporated into the crystal lattice of LiCoO 2 but converted by Li 2 O and Co 3 O 4 into PrCoO 3 and Li 3 PO 4 phases during the reaction. Additionally, these two phases are well-incorporated into the LiCoO 2 particle. Electrochemical tests indicate that the irreversible capacity during cycling is significantly reduced by PrPO 4 modification. Benefiting from the enhanced interface stability induced by Li 3 PO 4 and PrCoO 3 , the 1 mol% PrPO 4 -modified LiCoO 2 sample exhibits an initial discharge capacity of 185 mAhg −1 at 0.5C with a capacity retention of 92.4% after 100 cycles, as well as an excellent rate capability with a capacity of 128 mAhg −1 even at 5C.
To span the inherent application limitation of state-of-the-art catalysts for the chemical transformation of biomass derivatives, here, we formulate a series of Pr–Ni–P catalysts for the hydrogenation transformation of biomass-derived levulinic-acid, furfural and maleic anhydride. With comprehensive characterizations, Pr–Ni–P samples are verified as (PrPO4)m/Ni2P nanocomposites with a molar ratio (m) in the range of 0.24–11.0. In comparison with the poor catalytic performance of Ni2P, a ten-fold enhancement in TOF up to 0.45 s−1 and at least five-time promotion on the yield of objective products up to 91–98% are achieved by introducing proper amounts of PrPO4 to form reusable (PrPO4)m/Ni2P nanocomposites. Surface chemistry and kinetic mechanism studies further disclose that the cooperative catalytic function of two components, in particular the exclusive capability of PrPO4 to activate hydrogen, is responsible for the promoted hydrogenation transformation of biomass derivatives via a quick Langmuir–Hinshelwood process over (PrPO4)m/Ni2P. These findings imply that an easily obtainable, cost-affordable and robust rare earth phosphate like present PrPO4 could be a potential replacement catalytic component for the traditional metal catalyst in the hydrogenation transformation reactions of biomass derivatives, which was also worth noting as a new kind of basic material for other green mass-transformation techniques involving hydrogen activation processes such as corresponding optical and electrical transformations.
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