Investigation of Electrocatalytic Hydrogen Evolution Reaction (HER) Efficiencies of Phthalocyanines/Carbon-Boron Quantum Dots Nanoconjugates

We developed highly efficient electrocatalysts for hydrogen evolution through the noncovalent integration (via electrostatic and π-π 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. π–π 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 π-π 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 π-π stacked nanoconjugates offers a promising pathway for efficient hydrogen production, addressing both performance and cost considerations in renewable energy applications.