Non-Precious Tetra-(4-methylthiazole)-carboxamide Cobalt(II) Phthalocyanine Supported on Functionalized Carbon Nanotubes as an Efficient Electrocatalyst for a Hydrogen Evolution Reaction

Abstract

Hydrogen production by water splitting has gained significant attention due to a rise in demand for sustainable hydrogen fuel. In the present study, we report the synthesis of a novel, low-cost tetra-(4-methylthiazole)-carboxamide cobalt(II) phthalocyanine coordination polymer compound, denoted CoTMTCAPc, utilizing it as a catalyst for an electrocatalytic hydrogen evolution reaction (HER). This CoTMTCAPc compound shows satisfactory HER activity with an overpotential of 172 mV (vs RHE) at 10 mA cm –2 and a Tafel slope of 147 mV dec –1 . To further improve its electrocatalytic HER performance, the CoTMTCAPc compound is coupled with carboxyl-functionalized multiwalled carbon nanotubes (f-MWCNT). The synthesized CoTMTCAPc/f-MWCNT nanocomposite demonstrates HER activity on par with the benchmark Pt/C catalyst with an overpotential of 81 mV (vs RHE) at 10 mA cm –2 and a Tafel slope of 41 mV dec –1 with excellent stability. A mixture of CoTMTCAPc and bare MWCNT (without functionalization), on the other hand, does not give any notable hydrogen evolution activity. The piled-up CoTMTCAPc and f-MWCNT moieties are held together by van der Waals attraction and exhibit robust HER activity under harsh chemical conditions. Second, surface functionalities of f-MWCNT enhance dispersibility and assist in a homogeneous distribution of individual components, thereby improving charge-transfer interactions. The extraordinary HER performance of the CoTMTCAPc/f-MWCNT nanocomposite is attributed to abundant active sites due to homogeneously distributed CoTMTCAPc over f-MWCNT and improved electronic conductivity and charge-transfer rate. The coupling of the CoTMTCAPc moiety with f-MWCNT appears to be advantageous for electrocatalysis and other related applications.

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