Fe-incorporated cobalt-based metal-organic framework ultrathin nanosheets for electrocatalytic oxygen evolution

Abstract

Fe-incorporated Co-based ultrathin metal–organic framework catalysts (Fe(II) 1 Fe(III) 1 ) x /NMOF-Co) exhibits superior oxygen evolution reaction (OER) catalytic performance, and shines the new light for the real application of free-noble metal catalysts in electrocatalysis. • Controlled molar ratios of Fe to NMOF-Co inside Co-based ultrathin nanosheets is designed. • The ultrathin nanostructures provided extra active sites and enlarged active area. • High OER activity is achieved due to large ECSA and optimized molar ratios of Fe to MOF nanosheets. • The catalyst showed excellent catalytic activity and stability for OER. Rationally designing highly active electrocatalysts for the oxygen evolution reaction (OER) is exceedingly essential for ecologically sustainable development, but is still a principal research challenge due to the sluggish four-electron kinetics. Due to their structural diversity and ultra-high surface area, metal–organic framework (MOF) ultrathin nanosheets have expected to provide not only more accessible active sites, but also faster mass transfer and diffusion and have been realized as OER electrocatalysts. Therefore, we develop the controllable synthesis of Co-based MOF ultrathin nanosheets (NMOF-Co) incorporated with different-valence Fe ions, which are used as a high-performance electrocatalyst via a post-synthetic modification method. The binary metal electrocatalyst demonstrated more effective kinetics than the single metal electrocatalysts. By virtue, the obtained electrocatalyst with a uniform thickness of ~4.0 nm (defined as (Fe(II) 1 Fe(III) 1 ) 0.6 /NMOF-Co) sets in at potential of only 1.56 V with small Tafel slope of 50 mV . dec -1 , which is more superb than that of RuO 2 and bulk material Fe(II) 1 Fe(III) 1 ) 0.6 /Bulk-MOF-Co. The findings show that the structure of ultrathin nanosheets and the Fe incorporation are critical to the outstanding performance of MOF nanosheets for tuning the electrocatalytic activity, which is of great significance in the field of MOF electrocatalysis.