Degradation in photoelectrochemical devices: Review with an illustrative case study

The durability, reliability, and robustness of photoelectrochemical (PEC) devices are key factors for advancing the practical large-scale implementation of cost-competitive solar fuel production. We review the known degradation mechanisms occurring in water-splitting photoelectrochemical devices. The degradation of single components is discussed in detail, and the parameters and conditions which influence it are presented. Device short-term durability depends on the semiconductor material and its interface with the electrolyte. Catalyst and electrolyte degradations are considerable challenges for long-term durability. We highlight how PEC device design choices can affect the salience of alternative degradation mechanisms. The PEC device architecture and the initial operating design point are crucial for observed device performance loss. Device degradation behavior is further impacted by irradiation intensity and concentration, and by current density and concentration. Enhancing a physical understanding of degradation phenomena and investigating their effect on component properties is of utmost importance for predicting performance loss and tackling the durability challenge of PEC devices

A thermally synergistic photo-electrochemical hydrogen generator operating under concentrated solar irradiation

Achieving high current densities while maintaining high energy conversion efficiency is one of the main challenges for enhanc-ing the competitiveness of photo-electrochemical devices. We describe a concept that allows this challenge to be overcome by operating under concentrated solar irradiation (up to 474 kW m−2), using thermal integration, mass transport optimization and a close electronic integration between the photoabsorber and electrocatalyst. We quantify the increase in the theoretical maximum efficiencies resulting from thermal integration, and experimentally validate the concept using a III–V-based photoab-sorber and IrRuOx–Pt-based electrocatalysts. We reach current densities higher than 0.88 A cm−2 at calculated solar-to-hydro-gen conversion efficiencies above 15%. Device performance, dynamic response and stability are investigated, demonstrating the ability to produce hydrogen stably under varying conditions for more than two hours. The current density and output power (27 W) achieved provide a pathway for device scalability aimed towards the large-scale deployment of photo-electrochemical hydrogen production