The photosensitiser commonly serves as a single electron donor while two electrons are required for CO2to-CO conversion, which has led to the established practice to have excess photosensitiser in photocatalytic tests, with 20-50 times excess previously used. Initial photocatalytic tests herein used 20:1 RubpyC17 to CoPyPC16, which resulted in 52±2 catalyst turnovers for CO formation (TONCO) to give a turnover frequency (TOFCO) of 3.4±0.1 min -1 with selectivity for CO over H2 (SelCO) of 84±3% (Fig 1 , Table ). This is more selective than literature values for the water soluble catalyst variant (CoPyPC1) in aqueous phosphate buffer (SelCO 11%, 89% H2 formation), and comparable to a self-assembled liposome system (SelCO 77%). Ru photosensitisers are known to self-quench at high concentrations, which was mitigated herein by including the charge-neutral photocatalytically-inactive surfactant hexaethylene glycol monododecyl ether (C12E6; 1 CMC in H2O = 75 µM; Fig 1). The inclusion of the nominally inactive C12E6 surfactant increased the TONCO 5-fold to 249±38 for a TOFCO of 17±2 min -1 and SelCO of 87±2% (Fig 1 ), thereby demonstrating the importance of dispersing the photosensitisers in micelles to minimise selfquenching. Isotopic labelling with CO2 reveals that only CO is formed to confirm that all CO is formed from CO2 (Fig ). Exclusion controls show that the system is inactive if any of CO2, catalyst, photosensitiser, reductant or light are removed (Fig ). Amphiphilic RubpyC17 results in a 2.4-fold higher TOFCO and 30% higher CO selectivity than using its water-soluble hydrophilic analogue [Ru(bpy)3]Cl2 (Rubpy hereinafter, TOFCO of 6.8±0.8 min -1 ; Fig ), demonstrating the activity enhancement enabled by supramolecular self-assembly of the micellar system. .