The 1 O2 quantum yields of ZnPc, and ZnPc-AuNPs were found to be 0.56 and 0.66, respectively, Table , and these values are consistent with the findings reported in the existing literature for similar systems. The increase in the Δ value for ZnPc-AuNPs can be attributed to the plasmon resonance of AuNPs. Moreover, the 1 O2 of AuNPs alone is very low as reported previously, meaning that the AuNPs can generate 1 O2 when conjugated with PSs such as Pcs. The heavy atoms of AuNPs encourage intersystem crossing to the triplet state of the Pcs, enhancing the Pcs triplet population and thus 1 O2 quantum yield. . By applying a negative potential of -0.1 V at a graphite working electrode BQ can be reduced back to HQ. The electrochemically reduced product, HQ, can react again with 1 O2, thus, initiating a catalytic redox cycle. This redox cycle amplifies the amperometric response of the phenols, measured as a quantifiable photocurrent (Figure ). Thus, the larger 1 O2 production by the photosensitizer results in larger BQ production that also results in a stronger PEC response. of ZnPc. Thus, the illumination of the bare ZnPc with a 532 nm laser naturally yields significantly lower 1 O2 and, hence, a lower photocurrent response of only 50 nA in contrast to ~250 nA with the 659 nm red laser, Figure (a) and (b). However, as shown in Figure (c), the 532 laser matches perfectly with the absorption maximum of the LSPR band of the AuNPs.