Constructing pH-responsive smart material provides a new opportunity to address the problem that traditional electrocatalysts cannot achieve both alkaline oxygen evolution reaction (OER) and acidic hydrogen evolution reaction (HER) activities. In this study, amphoteric conjugated ligand (2-aminoterephthalic acid, BDC-NH2 )-modified 3d metal-anchored graphitic carbon nitride (3d metal-C3 N4 ) smart electrocatalysts are constructed, and self-adaptation of the electronic structure is realized by self-response to pH stimulation, which results in self-adjustment of alkaline OER and acidic HER. Specifically, the amino and carboxyl functional groups in BDC-NH2 undergo protonation and deprotonation respectively under different pH stimulation to adapt to environmental changes. Through DFT calculations, the increase or decrease of electron delocalization range brought by the self-response characteristic is found to lead to redistribution of the Bader charge around the modified active sites. The OER and HER activities are greatly promoted roughly 4.8 and 8.5 times over Co-C3 N4 after BDC-NH2 -induced self-adaptive processes under different environments, arising from the reduced energy barrier of O* to OOH* and ΔGH* . Impressively, the proposed BDC-NH2 -induced smart regulation strategy is applicable to a series of 3d metal anchors for C3 N4 , including Co, Ni and Fe, providing a general structural upgrading method for constructing smart electrocatalytic systems.
Keywords: carbon nitride; electrocatalysis; electronic structure; smart materials; water splitting.
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