Cobalt Phthalocyanine\nBased Metal–Organic Framework\nas an Efficient Bifunctional Electrocatalyst for Water Electrolysis

Abstract

Water\nis the most convenient and facile fossil-free source\nfor\nthe production of hydrogen (H₂). Electrochemical water\nsplitting is considered a promising and potential approach for accomplishing\nhydrogen frugality. Although water-splitting reaction is the most\nversatile and green technique, it accounts for only 4% of the universal\nH₂ production. The main hindrance in large-scale production\nis the sluggish kinetics of the reaction, which employs costlier and\nprecious catalysts. In addition, the half-cell reactions for the hydrogen\nevolution reaction (HER) and oxygen evolution reaction (OER) in water\nsplitting require two different types of precious catalysts, which\nnot only increases the cost but also decreases the efficiency due\nto the enhanced complexity of the system. Hence, designing an efficient,\nrobust, nonprecious, earth-abundant, and low-cost electrocatalyst\ncapable of catalyzing both HER and OER during overall water splitting\nis an urgent requirement to meet the energy demand for sustainable\ngrowth. Here, a highly potential bifunctional electrocatalyst is fabricated\nusing quinone-substituted cobalt(II) phthalocyanine (HQCoPc) with\ncarbon nanoparticles (Ketjen black, KB). The organic hybrid of HQCoPc\n+ KB modified on GCE and Ni foam showed remarkable electrocatalytic\nperformance for HER and OER in acidic and basic conditions, respectively.\nThe HQCoPc + KB composite affords a lower onset of 76 mV for HER and\nan overpotential of 234 and 360 mV at 10 mA·cm^–2 for HER and OER, respectively, with superior stability for more\nthan 40,000 s. The designed HQCoPc + KB bifunctional electrocatalyst\nnot only offers a better catalyst for addressing a water-splitting\nreaction but also provides cost-effectiveness and good chemical stability\nfor sustainable energy technology.