Photoelectrocatalysis (PEC) and photothermal catalysis place opposite demands on the light source. In PEC, uncontrolled heating distorts electrochemical data; in photothermal catalysis, converting light into heat is precisely the point. Confusing the two requirements is a common source of misinterpreted results.
PEC experiments record current under illumination while the cell is held at controlled temperature. Excess IR heats the electrolyte, accelerates side reactions and inflates photocurrents. Use IR-blocking filters or water jackets, calibrate intensity at the electrode plane, and run dark controls at matched temperature to separate photoresponse from thermomresponse. Monochromatic or narrow-band sources make IPCE measurements tractable.
Here the source should deliver high flux that the catalyst can convert to heat. Broadband xenon or concentrated solar-like illumination is preferred, and the measurement question shifts to temperature: record catalyst surface temperature, not just the bath or oven temperature, using IR imaging or embedded probes. Heating rate and light intensity both become experimental variables.
For photothermal claims, controls matter: the same catalyst heated electrically to the same surface temperature must show lower conversion than under light, otherwise the effect is not photothermal-specific. For PEC, the reverse control, illumination with thermal compensation, shows how much signal is genuinely photoelectric.
PEC wants narrow bands, IR suppression, calibrated moderate intensity and strict temperature control. Photothermal wants broadband, high flux, surface temperature measurement and thermal controls. The hardware overlaps, but the optics, filters and measurement plan do not.
Perfectlight's photothermal reaction systems and photoelectrocatalysis systems ship with source configurations matched to each regime; see light source solutions for details.
