Preparation of platinum-based 'cauliflower microarrays’ for enhanced ammonia gas sensing

Abstract

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Modification of Microelectrode Arrays with High Surface Area Dendritic Platinum 3D Structures: Enhanced Sensitivity for Oxygen Detection in Ionic Liquids

“…The platinum salt concentration (20 mM), lead acetate concentration (2 mM), and deposition potential (overpotential region, −0.2 V vs. Ag/AgCl) were fixed to observe the effect of the presence of lead acetate on the structure and shapes of the electrodeposits obtained. Cyclic voltammograms for some of the deposition processes in H 2 PtCl 6 /H 2 SO 4 were included in our previous work [ 18 ]. The different parameters employed are given in detail in the experimental section, and their abbreviations are given in the first column in Table 2 .…”

“…For the single-step deposits ( Figure 2 a,b,d,f), the deposits appear to have less material in the center of the structure. This is due to the greater contribution of (slower) linear diffusion within the pores, compared to the (faster) radial diffusion at the edges, resulting in more deposits growing over the edges [ 18 ]. In a two-step deposition, this hole becomes filled probably as a result of many new nucleation sites occurring in this region; this is demonstrated in Figure 2 d (one-step process) and 2e (two-step process), which both use a 420 s total deposition time.…”

“…RTILs are a class of solvent that possess several archetypal properties, such as negligible vapor pressures, high thermal and chemical stability, wide electrochemical windows, high polarity, high viscosity, intrinsic conductivity, and good solvation abilities [ 15 , 16 ]. Their near-zero volatility requires only very small quantities of solvent (down to as low as micro or nano-litre quantities in some cases) [ 17 , 18 , 19 , 20 ], and they can be dropcast onto the planar electrodes of miniaturized devices. This is of huge benefit compared to traditional solvents (e.g., water or organic solvents), which can evaporate in a relatively short amount of time, particularly in hot and dry conditions.…”

“…Arrays of microelectrodes can thus be employed with RTILs to improve current signals [ 13 , 14 ], but it is possible to further enhance their performance through improved electrode designs. We recently demonstrated this enhancement possibility by forming smooth, cauliflower shaped structures through electrodepositing platinum into the recessed holes of MATFEs, with overlapping diffusion zones roughly facing the adjacent electrodes [ 18 ]. These modified electrodes showed enhanced sensitivities for ammonia detection in ionic liquids [ 18 ], and these electrodes could be particularly beneficial for detecting highly toxic gases at low concentrations.…”

Hybrid Chemomechanical Promotion of PEDOT Adhesion onto Flexible Microelectrode Arrays for Chronic Neural Stimulation

“…This is the first time the mechanical integration of microporous material is combined with the electrochemical benefits of using diazonium salt in creating a hybrid composite that demonstrates long-standing strong adhesion between PEDOT and inorganic microelectrodes such as Pt. The major significance of this report is in highlighting the benefits of microporous solid-state coating technologies [21][22][23][24][25][26][27] as substrate materials for conductive material coatings while incorporating electrochemical adhesion promotion strategies such as diazonium salt.…”