CoMnFe hydroxysulfide nanowire@Ni(OH)2 nanorod arrays as self-supporting electrodes for high-efficiency oxygen evolution reaction

Multiscale Design of Array-Type Integrated Electrodes for Gas-Involving Electrocatalytic Reactions

Oxygen evolution/hydrogen evolution/oxygen reduction reactions (OER/HER/ORR) are core processes of electrochemical energy conversion technologies, which are of great significance to sustainable society. With the common gas-involving characteristic, these electrocatalytic reactions are inevitably faced with sluggish intrinsic kinetics at large current conditions, due to difficult mass transfer in multiphase conversion processes. Accordingly, array-type integrated electrodes are regarded as a promising solution, while relevant design strategies are systematically summarized from multiscale perspectives in this review. On one hand, macroscopic multidimensional structural designs are illustrated considering advantages and limitations of various one/two/three-dimensional (1D, 2D, 3D) array units; on the other hand, microscopic chemical/interfacial structural designs are emphasized by various strategies including ionic regulation, vacancy design, phase conversion, and interface engineering, etc. Furthermore, composite strategies are discussed in terms of surface, hierarchical, phase and atomic levels, especially on how to integrate macroscopic structural and microscopic chemical designs simultaneously. Finally, design rules of array-type integrated electrodes as well as outlooks for mass transfer strategies toward gas-involving reactions are provided.

An iron based organic framework coated with nickel hydroxide for energy storage, conversion and detection

Although electrode materials based on metal organic frameworks (MOFs) were widely studied in the electrochemistry field, the origin of poor conductivity is still a bottleneck restricting their development. Herein, we constructed a conductive circuit by growing a layer of hydroxide on the surface of the Fe-MOF, and composite materials (Fe-MOF@Ni(OH)₂) are applied in the fields of supercapacitor, OER, and electrochemical sensing. Fe-MOF@Ni(OH)₂ not only maintains the intrinsic advantages of Fe-MOF, but also improves the electrical conductivity. Fe-MOF@Ni(OH)₂ exhibits a high specific capacity of 188 mAh g^-1 at 1 A g^-1 . The energy density of the asymmetric supercapacitor (Fe-MOF@Ni(OH)₂-20//AC) reaches 67.1 Wh kg^-1. During the oxygen evolution reaction, the overpotential of the material is 280 mV at 10 mA cm^-2, and the Tafel slope is 37.6 mV dec^-1. The electrochemical sensing tests showed the detection limit of BPA is 5 μM. Hence, these results provide key insights into the design of multifunctional electrode materials.

Fe-Induced electronic optimization of mesoporous Co–Ni oxide nanosheets as an efficient binder-free electrode for the oxygen evolution reaction

An efficient binder-free OER electrode CoNiFeO_x/NF with mesoporous structure was synthesized by a facile strategy of hydrothermal method and post-annealing.