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

TLDR

Artificial‑leaf devices generate hydrogen by water splitting using two electrocatalyst electrodes powered by photovoltaics. The goal is to build an efficient, low‑cost artificial leaf using earth‑abundant materials. The authors present a lightweight electrode of NiCo₂O₄ nanorods anchored on carbon paper through nitrogen‑doped carbon nanotubes. The bifunctional electrode delivers 10 mA cm⁻² at 400 mV for both OER and HER, and when paired with a perovskite PV the artificial leaf reaches 100 % Faradaic H₂ efficiency, 6.2 % solar‑to‑hydrogen conversion, and a material payback time of about 100 days.

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 NiCo 2 O 4 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 H 2 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.