Soft lapping pads

UV-vis spectroscopy was conducted using a Shimadzu spectrometer UV-1800 and quartz cells with a 10 mm optical path. The absorbance was recorded from 800-300 nm and a baseline correction was conducted prior to all measurements.
All electrochemical experiments were conducted with a standard three-electrode system in a Faraday cage at 298K. The cyclic voltammetric measurements were performed using a Autolab II potentiostat (Metrohm-Autolab BV, Netherlands). Semi-circular potential wave sweep voltammetry was carried out with a computer-controlled in-lab built potentiostat ensuring the low-noise measurements with signal sampled at a stream rate of 100 kHz (Amin et al., 2019) (link). The potentiostat was controlled by script written in Python 3.5 to generate required potential waveform. For the voltammetric measurements, a glassy carbon (GC) macroelectrode (diameter calibrated as 2.99 mm) was used as the working electrode, a saturated calomel electrode (SCE, ALS distributed by BASi Inc., Japan.) as the reference electrode and a graphite rod as the counter electrode. The GC electrode was polished onto the soft lapping pads (Buehler, UK) with alumina (particles size of 1.0 and 0.3 m, Buehler, IL, UK) before each voltammetric experiment, followed by sonication in water and drying with nitrogen.

Anodic stripping experiments were performed with a µAutolab Type III potentiostat (Utrecht) using a glassy carbon working electrode (3 mm diameter, BASi, USA) and a platinum mesh counter electrode. A leakless Ag/AgCl (in 3.4 M KCl, eDAQ) or a saturated calomel electrode (BASi, USA) was used as a reference electrode.
Prior to use, the glassy carbon electrode was polished to a mirror finish using a water-alumina slurry (1.0 µm, 0.3 µm and 0.05 µm; Buehler, USA) on soft lapping pads (Buehler, USA). A 5 μL aliquot of the 48.2 pM AgNPs suspension was then dropcast onto the surface of the glassy carbon electrode and allowed to dry under a flowing nitrogen atmosphere. The AgNPmodified glassy carbon electrode was transferred to the electrolyte solution under studies (KNO 3 , KCl, KBr or KI). The system was then subjected to cyclic voltammetric measurements initially scanning anodically in the potential range of -0.4 V to 1.2 V vs. SCE at the scan rate of 10 mV s 1 .