Harnessing photocurrent enhancement in silver-bacterial cellulose nanocomposite for ultra-sensitive Hg²⁺ electrochemical detection

Figures & data

Figure 1. Schematic illustration of Bacterial cellulose production, acid hydrolysis and Nanocomposite formation.

Figure 2. Bacterial cellulose, nanomaterials and composite characterization (a) UV-Visible absorbance spectra;(b) FTIR spectra, TEM Micrographs of (c) NBC (Inset: unhydrolyzed Bacterial cellulose (BC)), and (d) AsAgNP-NBC blend (Inset: Zoomed in image of embedded AsAgNPs in the NBC matrix).

Figure 3. Optimization on three electrode system(a) Schematic of the 3-electrode system/set-up and electrode modification, (b) CV depicting detection of Hg²⁺ by the AsAgNP-NBC modified GCE at varying Hg²⁺ concentration from 10 nM to 2 µM, (c) Anodic region zoomed showing a shift in the anodic peak on interaction with increasing concentrations of mercury.

Figure 4. Photocurrent enhancement on modified SPE: (a) Schematic representation of the modified SPE and Photocurrent enhancement experiment; (b) CV measurements on AsAgNP-NBC modified SPE chip irradiated with 455 nm light source (Inset: Calibration plot representing oxidation signals measured on SPE irradiated with 455 nm light source with varying Hg²⁺ concentration (0.025–10 nM); (c) Comparative CV measurement of10nM Hg²⁺ on AsAgNP-NBC modified SPE chip with (Blue color) and without (Green color) irradiation, and (d) Anodic and Cathodic peak current comparison showing enhancement in peak currents after irradiation with 455 nm light.

Table 1. Comparison between anodic peak current, photocurrent enhancement and photoresponsivity of bare and modified SPE.

Type of SPE	Anodic Peak Current		Photoresponsivity
	Dark	With light (455 nm)
Bare SPE	7.81 µA	8.48 µA	8.7 × 10^−2mA W^−1
AsAgNP-NBC modified SPE	42.62 µA	81.23 µA	5.52 × 10^1 mA W^−1
Photocurrent enhancement	5.4 times	9.6 times

Figure 5. DPV measurements and selectivity experiments: (a) DPV measurements on AsAgNP-NBC modified SPE chip irradiated with 455 nm light source (Linear Range: 25 pM–50 nM) (b) DPV measurements on AsAgNP-NBC modified SPE chip without irradiation (Linear Range: 25 pM–50 nM), and (c) CV measurements conducted for interfering ions (Interfering metal ions concentration- 100 nM; Hg²⁺ concentration- 10 nM).

Table 2. Analytical data of the proposed sensing system with respect to CV and DPV measurements.

Electrode	Electrochemical Method	Linear Range	LOD
AsAgNP-NBC modified GCE	CV	10 nM–1 µM	3.531 nM
AsAgNP-NBC modified SPE	CV with irradiation	0.025 nM–10 nM	3.95 pM
	CV without irradiation	0.025 nM–10 nM	9.741 pM
	DPV with irradiation	0.025 nM–50 nM	2.717 pM
	DPV without irradiation	0.025 nM–50 nM	5.899 pM

Data availability statement

Data will be made available upon request.