Making Photocatalysis Comparable Using a Modular and Characterized Open‐Source Photoreactor**

Abstract

Reproducibility and comparability of photocatalytic experiments are still challenging, owing to the large number of experimental parameters and their comprehensive documentation. To overcome this limitation, a modular, adaptable, and extensible photoreactor platform is reported, which enables experiments under well‐characterized, reproducible conditions. Comparability is ensured by comprehensive photonic characterization with chemical actinometry, radiometry and open documentation of the incident photon fluxes in the reaction vessels for different setups as well as the homogeneity of irradiation in multi‐reactor setups. Comprehensive documentation minimizes the need for repeated photonic characterization when modifying the setups. Experimental reproducibility within and across experiments was evaluated with studies of photocatalytic systems for hydrogen evolution, emphasizing the validity of the concept.

Comparative Evaluation of Light‐Driven Catalysis: A Framework for Standardized Reporting of Data**

“…[81,82] The use of well-characterized or standardized reactor setups represents another approach to ensure reproducibility. [83][84][85][86][87] Furthermore, light-source aging needs to be considered; for instance, the intensity of mercury vapor lamps drops sharply during the first 500 hours and typically reaches 70 % of the initial intensity after 2000 hours of operations. In contrast, LEDs show a linear decrease of the emitted intensity and reach 70 % of the initial intensity after 20 000 hours.…”

“…Various laboratory scale reactors have recently been reported to address the challenges of comparability. [85,87,101,102] Specific chemical challenges, such as enhancing mass transport, have also been addressed using specialized spinning disc or oscillatory photoreactors. [103,104] Transferring synthesis from batch to continuous operation (e.g., with plug flow or (a series of) continuously stirred photoreactors) accelerates process optimization, improves handling of multiphase reaction systems, and accelerates transfer from lab to application.…”

Design and simulation of a uniform irradiance photochemical platform

“…5,[13][14][15] The number of photons absorbed by the reaction mixture depends on several factors including light intensity, emission profile of the light source, distance from the light source, geometry of the light, vessel, and surrounding environment and how fast the reaction is mixed. 13,[16][17][18][19][20][21][22] This complexity challenges the transferability of reaction conditions and reproducibility of photochemistry experiments. The issue becomes even more important in high throughput experimentation in which well plates, multiple vials, and flow reactors are used to run large numbers of reactions at high photon flux.…”

“…5,13,23 In order to address these issues, several custom photochemical platforms tailored for high throughput experimentation have been reported by commercial vendors as well as research labs. 13,15,16,19,21,22,[24][25][26][27][28][29][30][31][32][33][34] A large fraction of these platforms are designed for vials and seek to maximize photon flux by placing LEDs as close as possible to vials and/ or coating all surfaces with reflective material. 13,27,29 Common approaches for flow reactors have focused on matching LED position to flow paths, wrapping the reactor around a light source, or placing the light source around the reactor.…”

Comparative Studies of Oxygen‐Free Semiconductors in Photocatalytic CO2 Reduction and Alcohol Degradation

“…One possible reason that hinders the knowledge-driven development in this field has been the lack of comparability of reaction conditions in previous studies. Achieving truly reproducible and reliable reaction conditions in photocatalysis is a much more severe challenge in comparison to classical catalysis because the properties of the light source, such as irradiation intensity and spectrum, and the absorbed photon flux, must additionally be controlled [1]. Moreover, in CO 2 reduction, the deliberate or incidental presence of other carbon-containing molecules, such as sacrificial reagents, solvents, or grease-based sealing materials, must also be considered, as they can significantly contribute to the formation of carbonaceous products [2,3].…”