Tailoring electron transfer with Ce integration in ultrathin Co(OH)_(2) nanosheets by fast microwave for oxygen evolution reaction

The intrinsic activity of Co(OH)_(2) for oxygen evolution reaction(OER)may be elaborately improved through the suitable valence adjustment.Ce modification at electronic level is proved to be an efficient strategy owing to the flexible transformation of Ce^(3+)/Ce4+.Herein,Ce0.21@Co(OH)_(2) with the optimized Ce doping have been fabricated to tailor the fast electron transfer for the enhanced activity and stability for OER.Firstly,the obtained core-shell structure composed of vertical loose Co(OH)_(2) sheets not only exposes a large number of active sites,but also provides channels for Ce doping.Secondly,the high pressure microwave with instantaneous heating can fast introduce Ce into Co(OH)_(2),obtaining Cex@Co(OH)_(2) with well dispersion and close integration.The intimated interaction between Ce and Co species may provide the"d-f electronic ladders"for accelerating electron transfer of the catalytic surface.Meanwhile,Ce promotes the formation of Co-superoxide intermediate and/or the release of oxygen,which is considered to be the rate-determining step for OER.The electrochemical measurements confirmed the low overpotential of 300 m V at 10 m A cm^(-2) and great stability of Ce0.21@Co(OH)_(2) for OER.This work demonstrates a meaningful approach to realize the tuned electronic structure through metal doping.

Effective regulation mechanisms of Fe-Ni(oxy)hydroxide:Ni-rich heteroatomic bonding(Ni–O–Fe–O–Ni)is essential

Although Fe-Ni combination performs well in transition metal-based oxygen evolution reaction(OER)electrocatalysts,there are lack of clear and general regulations mechanism to fully play the synergistic catalytic effect.Here,we made the utmost of the interaction of Fe–Ni heteroatomic pair to obtain a highly active Fe-Ni(oxy)hydroxide catalytic layer on iron foam(IF)and nickel foam(NF)by in-situ electrochemical deposition and rapid surface reconstruction,which only required 327 and 351 mV overpotential to provide a large current of 1,000 mA·cm^(−2),respectively.The results confirm that the moderate Ni-rich heteroatomic bonding(Ni–O–Fe–O–Ni)formed by adjusting the Ni/Fe ratio on the catalyst surface is important to offer predominant OER performance.Fe is a key component that enhances OER activity of Ni(O)OH,but Fe-rich structural surface formed by Fe–O–Ni–O–Fe bonding is not ideal.Finally,the remarkable oxygen evolution performance of the prepared Ni2Fe(O)OH/IF and FeNi2(O)OH/NF can be chalked up to the optimized electronic structure of Fe–Ni heteroatomic bonding,the efficient gas spillover,the fast electron transport,and nanosheet clusters morphology.In summary,our work suggests a comprehensive regulation mechanism for the construction of efficient Fe-Ni(oxy)hydroxide catalytic layer on inexpensive,stable,and self-supporting metallic material surface.