Photophysical parameters. The 1 O2 and fluorescence quantum yield in DMSO for ZnPc, and ZnPc clicked to AuNPs were calculated using comparative methods reported elsewhere. Singlet oxygen quantum yield ( ∆ ) values are determined under ambient conditions using DPBF as a specific 1 O2 probe in DMSO. Unsubstituted ZnPc in DMSO was used as a standard  ∆ = 0.67 in DMSO. The absorbance of DPBF should be twice as much as the absorbance of Pcs (2:1) DPBF:Pc ratio. Equal-volume of quencher and photocatalyst was measured to conduct the 1 O2 study. To measure, 1 ml of DPBF and 1 ml of Pcs were mixed together in the cuvette and illuminated it with 670 nm laser at different time intervals. The absorbances of DPBF are spectroscopically monitored at 417 nm at predetermined time intervals. For fluorescence quantum yield (using unsubstituted phthalocyaninato zinc (II), as a standard, with  F = 0.20 all samples were excited at 670 nm and their emission spectra recorded from 600 nm to 800 nm. The solution of ZnPc, and ZnPc clicked to AuNPs for triplet state studies were flushed with argon for 20 min before measurements. Next, the lifetime was calculated by fitting the experimental datasets to single exponential using OriginPro 2015 program. Photoelectrochemical measurements. All electrochemical measurements were conducted in a three-electrode configuration with an upward-facing working electrode as described previously unless mentioned otherwise. The working electrolyte solution was prepared by mixing 3.675 mL CH3OH, 0.500 ml LiCl (0.1 M), 25 μL CH3COOH (AcOH) (5mM), 250 μL CH3COONa (AcONa) (5 mM), 500 μL PS (50 μM) and 50 μL of HQ (1 mM) which makes a total volume of 5 mL. The stock solutions of all the above components were prepared in CH3OH.