Improved sodium storage properties of nickel sulfide nanoparticles decorated on reduced graphene oxide nanosheets as an advanced anode material.

For sodium ion batteries, the fabrication of nanocrystal anode materials has been identified as a satisfactory strategy to improve electrochemical performance and maintain the structural integrity of electrodes. However, the issues of agglomeration and serious volume variation have always existed within the process of charging/discharging in anode materials. In this work, a series of composites of nickel sulfide nanoparticles decorated on reduced graphene oxide nanosheets (denoted as NiS2@rGO) were successfully synthesized via a simple one-step hydrothermal method under different temperatures. The strategy of confining nickel sulfide nanoparticles within the interlayer of graphene nanosheets can not only avoid the agglomeration, but also alleviate the volume change to some extent in electrode materials. For sodium ion storage, the NiS2@rGO synthesized at 160 °C exhibited a higher reversible capacity and better rate capability.

Construction of CoP@C embedded into N/S-co-doped porous carbon sheets for superior lithium and sodium storage.

To improve the electrical conductivity and relief the large volume variation, carbon coated CoP particles were designed to homogeneously embed into porous carbon sheets, which were synthesized though a simultaneous carbonization and phosphorization method. Notably, the uniform carbon shells and porous carbon sheets constructed a tough conductive matrix to enhance the electron transfer and structural stability during charging/discharging processes. Moreover, the heteroatom doping of nitrogen and sulfur could not only introduce more active sites and defects on the carbon sheets, but also increased electrical conductivity. Owing to the unique structure, the obtained material displayed good electrochemical performance for lithium storage (638.8 mA h g-1 at 0.2 A g-1 after 500 cycles and 334.9 mA h g-1 at 10 A g-1) and sodium storage (329.4 mA h g-1 at 0.2 A g-1 after 150 cycles and 162.4 mA h g-1 at 5 A g-1). More importantly, the reaction mechanism and the ion diffusion coefficient were explored by ex-situ XRD and EIS for both LIBs and SIBs. This versatile approach may avail to predigest the tedious phosphating process to obtain high-performance TMPs-based hybrids (such as Ni2P/C) by employing other metal salts.

Efficient depolymerization of Kraft lignin to liquid fuels over an amorphous titanium-zirconium mixed oxide supported partially reduced nickel-cobalt catalyst.

A series of non-precious metal/metal oxide nickel-cobalt catalysts was prepared for a highly efficient depolymerization of Kraft lignin (KL) into liquid fuels using amorphous TiZr-oxide (Ti1-yZryO2) as a carrier. The effects of Ni-NiOx, Co-CoOx, NiCo-NiCoOx, NiCoOx and NiCo catalysts supported on amorphous TiZr-oxide carrier on KL depolymerization were investigated. It was found that the NiCo-NiCoOx/Ti1-yZryO2 catalyst is optimal for converting KL to petroleum ether (PE)-soluble product (mainly composed of monomers and dimers) in an 80.2% high yield at 320 °C for 24 h, with excellent reusability and a low formation of char. Under these conditions, the higher heating value (HHV) increased from 25.11 to 33.89 MJ/kg. A meticulous study on NiCo-NiCoOx/Ti1-yZryO2 catalysts revealed that the synergistic effect among Lewis acid sites, basic sites and metal active sites played an important role in obtaining high yields of monomers and low rates of char formation during lignin conversion.

Efficient catalytic conversion of corn stalk and xylose into furfural over sulfonated graphene in γ-valerolactone.

Sulfonated graphene (SG) was prepared and employed to convert corn stalk and xylose into furfural. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize SG. The effects of reaction time, temperature, substrate loading, catalyst dosage and solvents on the reaction were researched and optimized. SG exhibited high catalytic activity in the conversion of xylose and corn stalk to furfural. A fairly high furfural yield of 96% was achieved at 150 °C from xylose and a 71.9% furfural yield was obtained when using a 10.7 ratio (mass ratio: xylose to SG) at 140 °C. While a 48% furfural yield was obtained from corn stalk (based on the starting combined moles of xylan and glucan in corn stalk; yield was >100%, if based on only xylan) using a substrate loading (corn stalk to catalyst mass ratio) of 2.14 and a 19% 5-hydroxymethylfurfural (5-HMF) yield was obtained. What's more, a 43.9% yield of furfural was obtained in only 20 min. In addition, the reusability of SG was also investigated and shown to have good stability for xylose dehydration.