07.04.21 – ISIC scientists report a hybrid bulk-heterojunction photoanode with benchmark performance for direct solar-to-chemical conversion

Photoelectrochemical (PEC) solar-to-chemical conversion is a promising form of “artificial photosynthesis” which directly converts power from the Sun into the chemical energy of molecular bonds (e.g. water splitting to H₂ and O₂), effectively storing solar energy as renewable chemical fuels and paving the way for a sustainable low-carbon economy. However, the development of high-performance and inexpensive semiconductor photoelectrodes that can also withstand the relatively harsh PEC operation conditions stands out as the main challenge in this field. Thinking “outside the box” scientists in the LIMNO and LPI labs at EPFL, have combined a robust in-situ formed covalent polymer network (CPN) with a mesoporous tin oxide in a bulk-heterojunction (BHJ) photoelectrode that overcomes limitations of both materials alone and demonstrates a new concept for photoelectrodes. Employed as a photoanode for PEC splitting of hydroiodic acid (HI), the inorganic-organic hybrid BHJ device delivered a solar photocurrent of 3.3 mA cm^–2 at the thermodynamic potential of iodide oxidation and a stable operation for 27 h, representing a new benchmark for hybrid photoanodes for solar-to-chemical conversion. The results have been published in the Royal Chemical Society’s premier energy journal Energy and Environmental Science.