High Solar-to-Hydrogen Conversion Efficiency at pH 7 Based on a PV-EC Cell with an Oligomeric Molecular Anode
Yuanyuan Shi, Tsung‐Yu Hsieh, Md Asmaul Hoque, Werther Cambarau, Stèphanie Narbey, Carolina Gimbert‐Suriñach, Emilio Palomares, Mario Lanza, Antoni Llobet
Abstract
In the urgent quest for green energy vectors, the generation of hydrogen by water splitting with sunlight occupies a preeminent standpoint. The highest solar-to-hydrogen (STH) efficiencies have been achieved with photovoltaic-electrochemical (PV-EC) systems. However, most PV-EC water-splitting devices are required to work at extreme conditions, such as in concentrated solutions of HClO4 or KOH or under highly concentrated solar illumination. In this work, a molecular catalyst-based anode is incorporated for the first time in a PV-EC configuration, achieving an impressive 21.2% STH efficiency at neutral pH. Moreover, as opposed to metal oxide-based anodes, the molecular catalyst-based anode allows us to work with extremely small catalyst loadings (<16 nmol/cm2) due to a well-defined metallic center, which is responsible for the fast catalysis of the reaction in the anodic compartment. This work paves the way for integrating molecular materials in efficient PV-EC water-splitting systems.