where 𝐽 𝑝ℎ is the photocurrent density, 𝑉 𝑎𝑝𝑝 is the applied bias (V vs. RHE), and 𝑃 is the incident light intensity (100 mW cm -2 ). Oxygen evolution was detected using a FireSting optical fiber oxygen meter (PyroScience, GmbH) in a home-made airtight two-compartment cell. The oxygen collection efficiency of approximately 42.6% ± 1.6% was determined electrochemically using a Pt working electrode in a 3-electrode system and assuming a standard faradaic efficiency (FE, based only on dissolved O2) of 100.0% ± 3.8%. The applied potential was 0.80 V vs. RHE, and the electrolyte was bubbled with argon before the measurement.