Visible light-active binary metal ion containing functional triazine metallopolymers as a stable p-type photo-electrocatalyst in protic electrolytes

Abstract

Visible light-active metallo-organic coordination systems have versatile opportunities due to their tunable electronic properties. Herein, we report a photocathode based on triazine trithiolate network polymers containing mixed metal ions of Cd²⁺ and Cu^2+/1+ with enhanced photoelectrochemical activity in acidic electrolytes. These thin films were prepared by the facile and direct chemical immobilization of cadmium ion containing triazine trithiolate units on a copper substrate through Cu–S linkage. The copper ions generated through controlled anodization enable the facile growth of mixed metal ion containing triazine trithiolate metallopolymers. The XPS analysis confirms the presence of Cd²⁺ and Cu^1+/2+ in the metallopolymeric thin films. Photoelectrochemical investigations suggest the p-type behavior with repeatable photocurrent of nearly 40–60 μA cm⁻² at higher reductive potentials (−0.6 V vs. Ag/AgCl) in 0.5 M H₂SO₄. Furthermore, these electrodes show −148 mV vs. RHE to attain 10 mA cm⁻² for hydrogen evolution in 0.5 M H₂SO₄ with good long-term surface stability even at high hydrogen evolution current densities from 350 to 500 mA cm⁻² or from 500 A g⁻¹ to 700 A g⁻¹.