THE ELECTROCATALYTIC ACTIVITY OF NiCo2O4 FOR THE OXYGEN EVOLUTION REACTION

A spinel oxide NiCo204 prepared by thermal decomposition is of very high activity for the oxygen evolution reaction(OER)in alkaline solution.The oxygen evolution overpotential on NiCo204 is 0.252-0.262V in 10 M NaOH solution at 343K and current density 100 mAcm^(-2).

Hierarchical cobalt-molybdenum layered double hydroxide arrays power efficient oxygen evolution reaction

Transition metal-based layered double hydroxides(LDHs)have been capable of working efficiently as catalysts in the basic oxygen evolution reaction(OER)for sustaining hydrogen production of alkaline water electrolysis.Nevertheless,exploring new LDH-based electrocatalysts featuring both remarkable activity and good stability is still in high demand,which is pivotal for comprehensive understanding and impressive improvement of the sluggish OER kinetics.Here,a series of bimetallic(Co and Mo)LDH arrays were designed and fabricated via a facile and controlled strategy by incorporating a Mo source into presynthesized Co-based metal-organic framework(MOF)arrays on carbon cloth(CC),named as ZIF-67/CC arrays.We found that tuning the Mo content resulted in gradual differences in the structural properties,surface morphology,and chemical states of the resulting catalysts,namely CoMox-LDH/CC(x representing the added weight of the Mo source).Gratifyingly,the best-performing CoMo_(0.20)-LDH/CC electrocatalyst demonstrates a low overpotential of only 226 mV and high stability at a current density of 10 mA·cm^(−2),which is superior to most LDH-based OER catalysts reported previously.Furthermore,it only required 1.611 V voltage to drive the overall water splitting device at the current density of 10 mA·cm^(−2).The present study represents a significant advancement in the development and applications of new OER catalysts.

Multicomponent transition metal phosphide for oxygen evolution

Transition metal phosphides(TMPs)have exhibited decent performance in an oxygen evolution reaction(OER),which is a kinetic bottleneck in many energy storages and conversion systems.Most reported catalysts are composed of three or fewer metallic components.The inherent complexity of multicomponent TMPs with more than four metallic components hinders their investigation in rationally designing the structure and,more importantly,comprehending the component-activity correlation.Through hydrothermal growth and subsequent phosphor-ization,we reported a facile strategy for combining TMPs with tunable elemental compositions(Ni,Fe,Mn,Co,Cu)on a two-dimensional ti-tanium carbide(MXene)flake.The obtained TMPs/MXene hybrid nanostructures demonstrate homogeneously distributed elements.They ex-hibit high electrical conductivity and strong interfacial interaction,resulting in an accelerated reaction kinetics and long-term stability.The res-ults of different component catalysts’OER performance show that NiFeMnCoP/MXene is the most active catalyst,with a low overpotential of 240 mV at 10 mA·cm−2,a small Tafel slope of 41.43 mV·dec−1,and a robust long-term electrochemical stability.According to the electrocata-lytic mechanism investigation,the enhanced NiFeMnCoP/MXene OER performance is due to the strong synergistic effect of the multi-ele-mental composition.Our work,therefore,provides a scalable synthesis route for multi-elemental TMPs and a valuable guideline for efficient MXene-supported catalysts design.

Self-assembled Nanohybrid from Opposite Charged Sheets:Alternate Stacking of CoAl LDH and MoS2

Hybrid materials are attracting intensive attention for their applications in electronics, photoelectronics, LEDs, field-effect transistors, etc. Engineering new hybrid materials and further exploiting their new functions will be significant for future science and technique development. In this work, alternatively stacked self-assembled CoAl LDH/MoS2 nanohybrid has been successfully synthesized by an exfoliation-flocculation method from positively charged CoAl LDH nanosheets（CoAl-NS） with negatively charged MoS2 nanosheets（MoS2-NS）. The CoAl LDH/MoS2 hybrid material exhibits an enhanced catalytic performance for oxygen evolution reaction（OER） compared with original constituents of CoAl LDH nanosheets and MoS2 nanosheets. The enhanced OER catalytic performance of CoAl LDH/MoS2 is demonstrated to be due to the improved electron transfer, more exposed catalytic active sites, and accelerated oxygen evolution reaction kinetics.