Photocatalytic CO2 reduction is one of the most attractive and one of the most misreported experiments in photocatalysis. Gas in, photons in, and a product slate of tiny amounts that must be quantified against rigorous controls. Building it on a proper platform keeps the difficulty manageable.
Sealed reactor with a gas inlet and outlet; CO2 purge path that establishes a known atmosphere; calibrated light source at the suspension; and an outlet routed to gas analysis, online detection or GC sampling. Every seal matters, leaks trade your products for air and destroy mass balance.
Typical products, CO, CH4, H2, sometimes methanol or formate in the liquid, appear at micromole scale. Use detectors whose limits sit well below your expected signal, calibrate in a CO2-rich humid matrix like the real headspace, and quantify every detectable product, selectivity computed on unmeasured products is fiction.
No-catalyst blank: does the system itself produce signal? No-light dark control: is anything thermal? Isotopic 13CO2 confirmation, when feasible, settles whether the carbon came from the feed or from residues. These three controls separate a real CO2 reduction result from an artifact, and reviewers now expect them.
Report light intensity and spectrum, reactor geometry, CO2 flow, catalyst loading, products with detection limits, and time-resolved production rates. Include the controls. A CO2 reduction paper without controls is a claim, not a result.
Perfectlight pairs sealed photoreactors with online gas analysis; see photocatalysis solutions for complete CO2 reduction setups.
