Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

Quantitative comparison of photocatalytic performances across different photocatalysis setups is technically challenging. Here, we combine the concepts of relative and optimal photonic efficiencies to normalize activities with an internal benchmark material, RuO 2 photodeposited on a P25-TiO 2 photocatalyst, which was optimized for reproducibility of the oxygen evolution reaction (OER). Additionally, a general set of good practices was identified to ensure reliable quantification of photocatalytic OER, including photoreactor design, photocatalyst dispersion, and control of parasitic reactions caused by the sacrificial electron acceptor. Moreover, a method combining optical modeling and measurements was proposed to quantify the benchmark absorbed and scattered light (7.6% and 81.2%, respectively, of λ = 300–500 nm incident photons), rather than just incident light (≈AM 1.5G), to estimate its internal quantum efficiency (16%). We advocate the adoption of the instrumental and theoretical framework provided here to facilitate material standardization and comparison in the field of artificial photosynthesis. • A highly reproducible photocatalyst, RuO 2 /TiO 2 , has been developed as a benchmark system for the oxygen evolution reaction • A concept of relative photonic efficiency using this benchmark is introduced • A method to estimate internal quantum efficiency is proposed • Best practices to ensure the reliable quantification of photocatalytic O 2 evolution data The continuous increase of atmospheric CO 2 levels at alarming rates has put photocatalytic water splitting in the spotlight as a source of “green” energy . However, quantitative comparison of photocatalytic activities across different labs remains challenging, since it involves multiple factors including light scattering and reactor design. Here, we propose two methods to compare photocatalytic performance for the oxygen evolution reaction (OER) across different setups, and put forward a set of good practices to ensure its quantification: first, a benchmark OER photocatalyst (RuO 2 /TiO 2 ) for the reliable determination of relative photonic efficiencies, and second, a procedure for estimating internal quantum efficiency by means of optical modeling and light-scattering measurements. These methods will open up new avenues for reliable comparison of photocatalytic performance across different laboratories and give a better overview and insight to the field. We present an approach to compare intrinsic