Last modified: 2014-10-11
Abstract
There has recently been a flurry of activity to create an improved "artificial leaf" for conversion and storage of intermittent solar energy in chemical form. An efficient system to realize this energy conversion requires integration of multiple functions: light absorption, excited-state charge separation, electron transfer activation of the catalytic site, and improved efficiency of the targeted reactions. Among the scheme, catalysis is the key. We will present several interesting systems by using copper in the catalysis of solar fuels production.
To lower the cost and improve efficiency and stability, efforts have been made to find efficient and robust first-row transition metal-based water oxidation catalysts, such as manganese, cobalt, nickel, copper and iron. Among these elements, copper is particular attractive but has been less explored for catalytic water oxidation. For example, the first copper-based homogeneous water oxidation catalyst was just reported in 2012. In the first part, we present several novel copper-based catalytic water oxidation catalysts and systems, including copper(II) ions in concentrated bicarbonate/carbonate, copper(II) polypeptide complexes, etc.
On the other hand, solar driven water splitting or CO2 reduction requires that both catalyst and electrode substrate do not obstruct the light transmission to dye or photovotaitic. For this purpose, ITO is typically used as a transparent electrode substrate and a thin-layer catalyst such as cobalt or nickel oxide or platinum was coated on ITO. However, ITO is expensive and ITO film is also fragile. Moreover, the use of thin-layer catalyst also limits the catalysis efficiency. In the second part, we present the using of Cu nanowires network as a conductive and transparent electrode substrate. The catalyst was then coated on Cu NWs to form a core-shell structure by electroplating. This core-shell structure nanowire network can replace the ITO/thin film catalyst system for solar fuels production and shows many advantages.