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    Investigation of Electrocatalytic Hydrogen Evolution Reaction (HER) Efficiencies of Phthalocyanines/Carbon-Boron Quantum Dots Nanoconjugates
    (Wiley-VCH GmbH, 2025) Karahan, Basak Gizem; Gumrukcu, Selin; Kaplan, Ekrem; Karazehir, Tolga; Unlu, Caner; Coskun, Ibrahim Yagiz; Ozcesmeci, Ibrahim
    We developed highly efficient electrocatalysts for hydrogen evolution through the noncovalent integration (via electrostatic and pi-pi interactions) of tetra-hydroxythioethyl-substituted metal-free (H2Pc) and cobalt(II) phthalocyanines (CoPc) with boron-doped carbon quantum dots (CBQdot). Incorporation of CBQdots greatly enhanced the molecular organization and uniformity of H2Pc and CoPc through strong interfacial interactions. pi-pi stacking, hydrogen bonding, and coordination between cobalt center and CBQdot surface groups led to well-ordered nanoconjugate systems. Raman analyses showed a decreased D/G ratio, particularly in CoPc/CBQdot, indicating defect passivation and improved interfacial ordering. SEM, EDX, and AFM results demonstrated reduced aggregation, smaller uniformly dispersed particles, and smoother, more continuous film morphologies. The hybrid CoPc/CBQD catalyst demonstrated exceptional HER activity in acidic media, significantly outperforming the CBQDots, H2Pc, and CoPc. Remarkably, the hybrid catalyst demonstrated superior hydrogen evolution reaction (HER) activity in acidic media, achieving a low overpotential of 434 mV at 10 mA cm-2 current density with a favorable Tafel slope of 124 mV dec-1. This enhanced performance originates from the synergistic pi-pi stacking interactions between the phthalocyanine core and the carbon quantum dots, which effectively modulates the catalyst's active surface area. Our findings present a technologically viable approach for developing noble-metal-free HER catalysts. The strategic design of these pi-pi stacked nanoconjugates offers a promising pathway for efficient hydrogen production, addressing both performance and cost considerations in renewable energy applications.