An electrochromic coordination nanosheet for robust CO2 photoreduction via ligand-based electron transfer

A coordination nanosheet composed of [Fe(tpy)(2)](2+) (tpy = 2,2':6',2 ''-terpyridine) units, showing reversible electrochromism at the ligand-based cathodic potential, has been prepared through a liquid/liquid interfacial synthesis. The noble metal-free nanosheet exhibited a CO evolution rate of 114.3 mmol.g(-1).h(-1) with the selectivity up to 99.3% under visible light irradiation in the presence of water, which is in the front rank of heterogeneous catalysis for CO2 photoreduction. Such robust photocatalytic performance is due to efficient ligand-based electron transfer through long-lived pi radical anion tpy(-) with a lifetime more than 25 min, as evidenced by in situ electron paramagnetic resonance (EPR) and ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy studies. Fe(II) cation in [Fe(tpy)(2)](2+) mainly contributes to enhancing reduction potentials of ligand and stabilizing pi radical anion tpy(-). This ligand-based electron transfer with the aid of metal cation represents a promising strategy for selective CO2 photoreduction, especially towards gaining CO from CO2.

Automated summary

A coordination nanosheet composed of [Fe(tpy)(2)](2+) units was prepared through a liquid/liquid interfacial synthesis, showing reversible electrochromism and excellent CO2 photocatalytic performance. The robust photocatalytic performance is attributed to efficient ligand-based electron transfer through long-lived pi radical anion tpy(-).