Authors
Suparna Roy, Manjula Pal, Pritam Ghosh, Mahasweta Nandi, Partha Roy
Published in
Dalton transactions (Cambridge, England : 2003). Aug 17, 2026. Epub Aug 17, 2026.
Abstract
Ni(II) complexes have been used as electrocatalysts in the hydrogen evolution reaction (HER) to produce clean, environmentally friendly fuel. Geometry around the metal centre may play a crucial role in its electrocatalytic activities. For this purpose, two nickel complexes, [Ni(L1)2] (complex 1) and [Ni(L2)NO3] (complex 2), where HL1 = 1-((2-(pyrrolidin-1-yl)ethylimino)methyl)naphthalen-2-ol and HL2 = 1-((3-((3-aminopropyl)(methyl)amino)propylimino)methyl)naphthalen-2-ol, were synthesized and characterized by different standard methods, including single crystal X-ray diffraction analysis. The Ni in complex 1 is characterized by a square planar geometry, and the metal center in complex 2 is hexacoordinated. Various experiments reveal that (i) the diffusion coefficient of complex 1 (18.01 × 10-2 cm2 s-1) is higher than that of complex 2 (3.45 × 10-2 cm2 s-1), (ii) the overpotential values are 0.47 V and 0.56 V for complex 1 and complex 2, respectively, (iii) the TOF values are 389.5 and 182.5 for complex 1 and complex 2, respectively, and (iv) the faradaic efficiency is 90% for complex 1 and 86% for complex 2. On the basis of the electrochemical results and the DFT-optimized local-minimum structures, an ECEC-type HER pathway is proposed, although other proton-/electron-transfer sequences cannot be ruled out from the present data. These results suggest more robust catalytic activity of complex 1 than complex 2 in the HER.
PMID:
42605615
Bibliographic data and abstract were imported from PubMed on 17 Aug 2026.
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