posted on 2021-02-04, 13:34authored byMeihui Ying, Rui Tang, Wenjie Yang, Weibin Liang, Guizeng Yang, Haibo Pan, Xiaozhou Liao, Jun Huang
The
performance-limiting half reaction of electrochemical water
splitting is the anodic oxygen evolution reaction (OER). The increased
adsorption, especially chemical adsorption capacity, of the OER intermediate
*O on anode materials is one of the key factors to improve the performance
of the anodic electrocatalysts. In this research, we tuned the electronegativity
of anode materials to tailor their chemical adsorption capacity in
OER by modulating the metal ion composition in the secondary building
unit in metal–organic frameworks (MOFs). Nanosheet Fe(III)-MIL-88A
has been prepared as a parent catalyst in this research due to its
high charger transfer capability and stability. Ni2+ ions
with lower electronegativity have been introduced to exchange Fe3+ sites in Fe(III)-MIL-88A, which would lead to decrease of
the overall electronegativity of the MOF anode, accompanied by the
electron density shift from Ni2+ to Fe3+ via
bridge oxygen. Porous MOFs with lower overall electronegativity significantly
improved their adsorption capacity for *O intermediate, thereby accelerating
the OER performance during operation. Our research hints at the potential
that the electronegativity of porous anodes could be fine-tuned to
optimize their adsorption capability for the high-efficient hydrogen
production during electrocatalytic water splitting.