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

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