Light addressable electrochemical (LAE) sensors have seen great utility in the past several years because they enable multiple localized electrochemical measurements to be performed on a single macroscopic electrode, opening up applications in imaging, biosensing, surface patterning, and multiplexing. In this study, we investigated the effects of electrodeposition on the formation of LAE sensors formed between n‐Si and electrodeposited Pt. We prepared sensors by electrodepositing Pt onto freshly‐etched n‐Si under a variety of conditions, varying the Pt precursor concentration, electrodeposition time, supporting electrolyte, and potential waveform. We characterized the sensors using a combination of atomic force microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. This study shows that the electrodeposition parameters have a dramatic impact on the morphology of the electrodeposited surfaces, sensor stability, and sensitivity towards H2O2. Specifically, we observed that continuous Pt films prepared with a higher Pt precursor concentration were more stable and had better linearity, higher sensitivity, and broader dynamic range than those prepared with a lower Pt precursor concentration. The stability and increased H2O2sensing performance correlate strongly with an increase in the Pt islands which make up the film. These data highlight that the morphology of the metal in semiconductor/metal junction LAE sensors has an impact on important performance metrics like stability and sensitivity. They also demonstrate the need for semiconductor/metal LAE sensors to be studied using micro‐ and nanoscale imaging techniques in order to more deeply understand their performance characteristics.
Light-Addressable Electrochemical Sensing with Electrodeposited n‑Silicon/Gold Nanoparticle Schottky Junctions
Light-addressable electrochemical sensors (LAESs) are a class of sensors that use light to activate an electrochemical reaction on the surface of a semiconducting photoelectrode. Here, we investigate semiconductor/metal
(Schottky) junctions formed between n-type Si and Au nanoparticles as lightaddressable electrochemical sensors. To demonstrate this concept, we prepared n-Si/Au nanoparticle Schottky junctions by electrodeposition and characterized them using scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. We found that the sensors behaved almost identically to Au disk electrodes for the oxidation of an outer-sphere redox couple (ferrocene methanol) and two inner-sphere redox couples (potassium ferrocyanide and dopamine). In buffered dopamine solutions, we observed broad linear ranges and submicromolar detection limits. We then used local illumination to generate a virtual array of electrochemical sensors for dopamine as a strategy for circumventing sensor fouling, which is a persistent problem for electrochemical dopamine sensors. By locally illuminating a small portion of the photoelectrode, many measurements of fouling analytes can be made on a single sensor with a single electrical connection by moving the light beam to a fresh area of the sensor. Altogether, these results pave the way for Schottky junction light-addressable electrochemical sensors to be useful for a number of interesting future applications in chemical and biological sensing.
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- Award ID(s):
- 1909824
- NSF-PAR ID:
- 10212814
- Date Published:
- Journal Name:
- Analytical chemistry
- Volume:
- 92
- ISSN:
- 0003-2700
- Page Range / eLocation ID:
- 11444-11452
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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