Toward a Low-Cost Artificial Leaf: Driving Carbon-Based and Bifunctional Catalyst Electrodes with Solution-Processed Perovskite Photovoltaics

This time we report an artificial-leaf device where NiCo2O4 nanorods are used as bifunctional electrode that it can operate as both anode and cathode in the same alkaline solution. By driving two such identical electrodes with a perovskite photovoltaic assembly, a wired artificial-leaf device is obtained that features a Faradaic H2 evolution efficiency of 100%, and a solar-to-hydrogen conversion efficiency of 6.2%. This work was carried out in close collaboration with the research groups of Prof. Edman and Prof. Messinger. The article is published in the journal of Advanced Energy Materials as open access.

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Tiva Sharifi, Christian Larsen, Jia Wang, Wai Ling Kwong, Eduardo Gracia-Espino, Guillaume Mercier, Johannes Messinger, Thomas Wågberg, and Ludvig Edman.
Adv. Energy Mater. 2016, DOI: 10.1002/aenm.201600738

Abstract

Molecular hydrogen can be generated renewably by water splitting with an “artificial-leaf device”, which essentially comprises two electrocatalyst electrodes immersed in water and powered by photovoltaics. Ideally, this device should operate efficiently and be fabricated with cost-efficient means using earth-abundant materials. Here, a lightweight electrocatalyst electrode, comprising large surface-area NiCo2O4 nanorods that are firmly anchored onto a carbon–paper current collector via a dense network of nitrogen-doped carbon nanotubes is presented. This electrocatalyst electrode is bifunctional in that it can efficiently operate as both anode and cathode in the same alkaline solution, as quantified by a delivered current density of 10 mA cm−2 at an overpotential of 400 mV for each of the oxygen and hydrogen evolution reactions. By driving two such identical electrodes with a solution-processed thin-film perovskite photovoltaic assembly, a wired artificial-leaf device is obtained that features a Faradaic H2 evolution efficiency of 100%, and a solar-to-hydrogen conversion efficiency of 6.2%. A detailed cost analysis is presented, which implies that the material-payback time of this device is of the order of 100 days.