Photoelectrocatalysis claims that light and applied bias do something together that neither does alone. The claim is testable, but only with a control design that separates the contributions cleanly. Here is the experiment structure that makes the argument.
Four conditions on the same electrode: (1) dark, no bias, (2) dark with bias, (3) light, no bias, (4) light with bias. Synergy in the strict sense means condition 4 outperforms the sum of the individual contributions of 2 and 3 over 1. Anything less is addition, not cooperation, and the distinction matters for how the system is described.
Temperature: illuminated electrodes warm up, and thermal gains masquerade as synergy. Monitor surface or electrolyte temperature and match it across conditions. Intensity: measure and report photon flux at the electrode. Electrolyte history: run conditions in an order that avoids contamination carryover, and randomize or alternate when deactivation is possible.
Current (or rate), product amounts and selectivity. Synergy can appear in rate, in selectivity or in stability, and each requires the same four-condition structure to be meaningful. Faradaic efficiency per condition reveals whether bias changes what the photogenerated charges do, often the most interesting result.
Show all four conditions in one figure with identical axes, state the temperature control and the photon flux, and let the comparison speak. Reviewers discount synergy claims shown as two bars, they believe four-condition matrices with error bars.
Perfectlight's electrochemical workstations and light sources are built for these paired-control campaigns; see solutions.
