Substituent group-tunable hydrogen evolution activity observed in isostructural Cu(II)-based coordination polymer photocatalysts.

Elucidations on the structure–activity correlations of non-Pt coordination polymer (CP)-based photocatalysts are highly significant for both the enhancement in catalytic activity and large-scale industrial applications of sustainable hydrogen from water splitting. Herein, three isostructural [Cu(HL) 2 (R-BDC)] n (denoted as Cu-CP-R, HL = 4′-(4-hydroxyphenyl)-4,2′:6′,4′′-terpyridine, R-BDC = 2-R-1,4-benzenedicarboxylate, R = NO 2 , OH and Br) CPs were solvothermally synthesized by varying the substituents attached to benzenedicarboxylate, which together with two previously reported analogues (R = NH 2 and H) were used as photocatalysts to systematically explore the substitution effect on the hydrogen evolution activity. These five CPs feature isomorphic layered motifs with axially elongated Cu II octahedra extended alternately by ditopic HL and R-BDC 2− connectors, in which R behaves structurally as a non-coordinate group. The hydrogen production rate over the Cu-CP-R photocatalysts increased from 0.21 to 2.34 mmol g −1 h −1 , which followed the order of –NH 2 > –NO 2 > –H > –OH > –Br. Furthermore, the combined experimental and theoretical investigations reveal that the free R moiety significantly dominates the photocatalytic activity by shifting the d states of the Cu II ion towards the Fermi level, controlling the potential of the conduction band and quickening the charge transfer ability. These important findings can provide informative hints for the design of high-performance, earth-abundant non-noble metal CP-based semi-conductive photocatalysts. [ABSTRACT FROM AUTHOR]

Copyright of Dalton Transactions: An International Journal of Inorganic Chemistry is the property of Royal Society of Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)