Stand-Alone Photoelectrochemical Energy Conversions

The photoelectrochemical (PEC) conversions of water and atmospheric CO2 to value-added fuels, such as H-2, CH4, and CH3OH, can provide potential alternative sources for clean and environment-friendly solar fuels. Several efforts are reported on the designing and developing stand-alone PEC cells that efficiently produce H-2 and O-2 from water and minimize atmospheric CO2 via conversion to fuels under only sunlight. However, in reality, high overpotential, poor product-selectivity, competitive side-reactions, and self-reduction of a catalyst limit the performance of the PEC cells, thereby requiring high power inputs. The choice of electrode materials and architectures of PEC cells are very important for designing stand-alone and durable PEC cells with high solar-to-fuels conversion efficiency (Eff(STF)) and high selectivity. The present review provides a complete account of recent published works on stand-alone PEC systems with different architectures; development of electrode materials for high Eff(STF), selectivity, and stability; and the current challenges. Furthermore, this review describes the future outlook on stand-alone PEC systems for future production of clean solar fuels and mitigation of atmospheric CO2 levels by utilizing only solar energy.

Automated summary

Photoelectrochemical conversion of water and CO2 to fuels offers potential alternative sources for clean solar fuels, but current challenges including high energy consumption and low selectivity need to be addressed. Designing efficient, selective, and stable stand-alone PEC cells with appropriate electrode materials and architectures is crucial for future production of clean solar fuels.