Transition-metal sulfides (TMSs) have emerged as important candidates for oxygen evolution reaction (OER) electrocatalysts. Now a hybrid nanostructure has been decorated with CeO nanoparticles on the surface of ZIF-67-derived hollow CoS through in situ generation. Proper control of the amount of CeO on the surface of CoS can achieve precise tuning of Co /Co ratio, especially for the induced defects, further boosting the OER activity. Meanwhile, the formation of protective CeO thin layer effectively inhibits the corrosion by losing cobalt ion species from the active surface into the solution. It is thus a rare example of a hybrid hetero-structural electrocatalyst with CeO NPs to improve the performance of the hollow TMS nanocage.

Developing convenient doping to build highly active oxygen evolution reaction (OER) electrocatalysts is a practical process for solving the energy crisis. Herein, a facile and low-cost in situ self-assembly strategy for preparing a Ce-doped NiFe-LDH nanosheets/nanocarbon (denoted as NiFeCe-LDH/CNT, LDH = layered double hydroxide and CNT = carbon nanotube) hierarchical nanocomposite is established for enhanced OER, in which the novel material provides its overall advantageous structural features, including high intrinsic catalytic activity, rich redox properties, high, flexible coordination number of Ce, and strongly coupled interface. Further experimental results indicate that doped Ce into NiFe-LDH/CNT nanoarrays brings about the reinforced specific surface area, electrochemical surface area, lattice defects, and the electron transport between the LDH nanolayered structure and the framework of CNTs. The effective synergy prompts the NiFeCe-LDH/CNT nanocomposite to possess superior OER electrocatalytic activity with a low onset potential (227 mV) and Tafel slope (33 mV dec), better than the most non-noble metal-based OER electrocatalysts reported. Therefore, the combination of the remarkable catalytic ability and the facile normal temperature synthesis conditions endows the Ce-doped LDH nanocomposite as a promising catalyst to expand the field of lanthanide-doped layered materials for efficient water-splitting electrocatalysis with scale-up potential.

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This paper presents a numerical study of the gas-powder-liquid flow in a standard hydrocyclone. In the approach, the turbulent fluid flow is described by the Reynolds stress model, the interface between the liquid and air core is modeled using the volume of fluid multiphase model, and the results of fluid flow are used in the simulation of particle flow described by the stochastic Lagrangian model. The flow features are examined in terms of flow field, pressure drop, volume split ratio reported to the underflow, particle trajectories, and separation efficiency. The validity of the proposed approach is verified by the good agreement between the measured and the predicted results. Discussion is then extended to other flow behavior in a hydrocyclone, including the origin of a short-circuiting flow, the structure of air core, and the motion of particles of different sizes. The model offers a convenient method to investigate the effects of variables related to geometrical and operational conditions on the performance of hydrocyclone.