Ultrathin Metal-Organic Framework Nanosheets-Derived Yolk-Shell Ni_(0.85)Se@NC with Rich Se-Vacancies for Enhanced Water Electrolysis

We present a controlled fabrication of selective ultrathin metal-organic framework(MOF)nanosheets as preassembling platforms,yolk-shell structured with a few-layered N-doped carbon(NC)shell-encapsulated Ni_(0.85)Se core(denoted as Ni_(0.85)Se@NC)via an oriented phase modulation(OPM)strategy.The ultrathin nature of the MOF nanosheets gave rise to the modification of structure at the electronic level with abundant Se-vacancies and effective electronic coupling via an Ni-N_(x) coordination at the interface between the Ni0.85Se core and NC shell.The Ni0.85Se@NC obtained exhibited low overpotentials for both oxygen evolution reaction(OER;300 mV)and hydrogen evolution reaction(HER;157 mV)at 10 mA·cm^(−2) under an alkaline condition,outperforming their corresponding bulk MOF-derived counterparts.By exploiting Ni_(0.85)Se@NC as anode and cathode catalysts,a low cell voltage of 1.61 V was achieved by performing alkaline water electrolysis.Remarkably,it also reached a high activity in natural seawater(pH=7.98)and simulated seawater(pH=7.86)electrolytes,even surpassing integrated Pt/C-RuO_(2)/CC electrodes.Density functional theory(DFT)studies illustrated that abundant Se-vacancies effectively regulated the electronic structure of Ni_(0.85)Se@NC by accelerating electron transfer from Ni to N atoms at the interface,and thus,enabling the Ni_(0.85)Se@NC to attain a near-optimal electronic configuration that stimulated ideal adsorption-free energy toward key reaction intermediates.

Bimetallic Au-Pd NPs Embedded in MOF Ultrathin Nanosheets with Tuned Surface Electronic Properties for High-performance Benzyl Alcohol Oxidation

Bimetallic Au-Pd nanoparticles(NPs)with synergistic effect between Au and Pd atom have shown excellent catalytic activity toward benzyl alcohol oxidation.The catalytic activities of metal NPs supported within metal-organic frameworks(MOFs)are affected by the electronic interactions between metal NPs and MOFs.Taking the advantages of ultrathin nanosheets,we confine the highly dispersed Au-Pd NPs within ultrathin nanosheets of MOF-Ni(NMOF-Ni)to fabricate Au_(x)Pd_(y)@NMOF-Ni as catalysts.Under base-free and atmospheric pressure conditions,the as-prepared Au_(x)Pd_(y)@NMOF-Ni catalysts exhibit superior activity and selectivity for benzyl alcohol oxidation.This work highlights the synergistic effects among different components in composite catalysts effectively improving the activity and offers a new way for designing efficient catalysts toward benzyl alcohol oxidation.