Graphene oxide interlayered Ga-doped FeSe2 nanorod: A robust nanocomposite with ideal electronic structure for electrochemical dopamine detection

Metal doping in the crystal lattice of metal selenide has proven to improve its conductivity and electrocatalytic activity. However, finding a suitable dopant that can tune its electronic structure for effective biomolecular detection is still a challenge. Herein, we investigate gallium (Ga3+) and amine-functionalized graphene oxide (fGO) as an effective dopant and support for FeSe2 using a facile solvothermal and hydrothermal method. The sensing ability of the resulting composite towards dopamine (DA) is determined using differential pulse voltammetry. Our results show that Ga3+ effectively dopes the FeSe2 lattice by replacing Fe2+ and maximizes the conductivity of FeSe2 at x = 0.7 (Ga0.7Fe0.3Se2) which leads to enhanced sensitivity towards DA. However, Ga0.7Fe0.3Se2 is unstable, non-selective and detects DA at a high potential. Nevertheless, after its intercalation in between fGO sheets, Ga0 Fe0.3Se2 stabilizes and it is able to selectively detect DA at a significantly lower potential for a long time without loss in activity. The synergy between fGO and GaxFe1-xSe2 thus allows trace amounts of DA to be detected with a LOD of 110 nM within a DA range of 2-170 mu M. This study shows that Ga3+ is an excellent dopant for FeSe2 while intercalation within fGO sheets boost stability and selectivity. (C) 2020 Elsevier Ltd. All rights reserved.