A new approach for the improved interpretation of capacitance measurements for materials utilised in energy storage

A simple galvanostatic circuit methodology is reported allowing the capacitance of an electrochemical electrolytic capacitor to be accurately measured, without recourse to expensive instrumentation. The method avoids problems found in current electrochemical impedance spectroscopy analysis, which give rise to profiles that may result in false or inaccurate derivation of the electrolytic capacitance. The advantages of this approach are that the circuit is easy and cheap to fabricate. The system is linear, regardless of the texture of the electrode and the type of electrolyte, and the measurement is direct so that no presumable equivalent circuit model is required. Such work is highly important for those developing new materials in energy storage, as it allows the reliable measurement of capacitance to be achieved without the need for expensive or complex instrumentation. This paper also highlights that users are more informed through checking capacitances using a variety of techniques, though such a circuit could in theory eliminate the need for affirmation of values utilising other electrochemical methods/techniques

2D Hexagonal Boron Nitride (2D-hBN) Explored for the Electrochemical Sensing of Dopamine

© 2016 American Chemical Society. Crystalline 2D hexagonal boron nitride (2D-hBN) nanosheets are explored as a potential electrocatalyst toward the electroanalytical sensing of dopamine (DA). The 2D-hBN nanosheets are electrically wired via a drop-casting modification process onto a range of commercially available carbon supporting electrodes, including glassy carbon (GC), boron-doped diamond (BDD), and screen-printed graphitic electrodes (SPEs). 2D-hBN has not previously been explored toward the electrochemical detection/electrochemical sensing of DA. We critically evaluate the potential electrocatalytic performance of 2D-hBN modified electrodes, the effect of supporting carbon electrode platforms, and the effect of "mass coverage" (which is commonly neglected in the 2D material literature) toward the detection of DA. The response of 2D-hBN modified electrodes is found to be largely dependent upon the interaction between 2D-hBN and the underlying supporting electrode material. For example, in the case of SPEs, modification with 2D-hBN (324 ng) improves the electrochemical response, decreasing the electrochemical oxidation potential of DA by ∼90 mV compared to an unmodified SPE. Conversely, modification of a GC electrode with 2D-hBN (324 ng) resulted in an increased oxidation potential of DA by ∼80 mV when compared to the unmodified electrode. We explore the underlying mechanisms of the aforementioned examples and infer that electrode surface interactions and roughness factors are critical considerations. 2D-hBN is utilized toward the sensing of DA in the presence of the common interferents ascorbic acid (AA) and uric acid (UA). 2D-hBN is found to be an effective electrocatalyst in the simultaneous detection of DA and UA at both pH 5.0 and 7.4. The peak separations/resolution between DA and UA increases by ∼70 and 50 mV (at pH 5.0 and 7.4, respectively, when utilizing 108 ng of 2D-hBN) compared to unmodified SPEs, with a particularly favorable response evident in pH 5.0, giving rise to a significant increase in the peak current of DA. The limit of detection (3σ) is found to correspond to 0.65 μM for DA in the presence of UA. However, it is not possible to deconvolute the simultaneous detection of DA and AA. The observed electrocatalytic effect at 2D-hBN has not previously been reported in the literature when supported upon carbon or any other electrode. We provide valuable insights into the modifier-substrate interactions of this material, essential for those designing, fabricating, and consequently performing electrochemical experiments utilizing 2D-hBN and related 2D materials

2D Hexagonal Boron Nitride (2D-hBN) Explored as a Potential Electrocatalyst for the Oxygen Reduction Reaction

Crystalline 2D hexagonal Boron Nitride (2D-hBN) is explored as a potential electrocatalyst towards the oxygen reduction reaction (ORR) when electrically wired via a drop-casting approach upon a range of carbon based electrode surfaces; namely, glassy carbon (GC), boron-doped diamond (BDD), and screen-printed graphitic electrodes (SPEs). We consider the ORR in acidic conditions and critically evaluate the performance of unmodified and 2D-hBN modified electrodes, implementing coverage studies (commonly neglected in the literature) in order to ascertain the true impact of this novel nanomaterial. The behaviour of 2D-hBN towards the ORR is shown to be highly dependent upon both the underlying carbon substrate and the coverage/mass utilised. 2D-hBN modified SPEs are found to exhibit the most beneficial response towards the ORR, reducing the peak potential by ca. 0.28V when compared to an unmodified/bare SPE. Such improvements at this supporting substrate are inferred due to favourable 2D-hBN interaction with ridged surfaces exposing a high proportion of edge regions/sites, where conversely, we show that relatively smooth substrate surfaces (such as GC) are less conducive towards successful 2D-hBN immobilisation. In this paper, we reveal for the first time (in the specific case of using a rough supporting substrate) that 2D-hBN gives rise to beneficial electrochemical behaviour towards the ORR. Unfortunately, this material is not considered an electrocatalyst for use within fuel cells given that the estimated number of electrons transferred during the ORR ranges between 1.90-2.45 for different coverages, indicating that the ORR at 2D-hBN predominantly produces hydrogen peroxide. 2D-hBN does however have potential and should be explored further by those designing, fabricating and consequently electrochemically testing modified electrocatalysts towards the ORR

Five years of the #RSCPoster Twitter conference

The #RSCPoster Twitter conference is an annual, 24 hour poster conference held each March on Twitter. This original conference format has enabled hundreds of participants to share their research, with 32 million measurable impressions of #RSCPoster in 2020, participation growing each year and inspiring new conferences. Here, we will give a brief outline of the history, technicalities and content of the event

The latest developments in quantifying cyanide and hydrogen cyanide

Cyanides are highly poisonous in small quantities, yet are used in a variety of applications on a daily basis amounting to a global annual usage of around 1.1 million tonnes. With the usage of cyanides not decelerating, it is imperative for analytical chemists to devise methods of detection to ensure safe usage and working conditions, as well as methods to determine concentrations in blood for patients who may have been over-exposed to cyanides or in breath for Cystic Fibrosis sufferers who contract HCN-producing bacterial infections. This review introduces the synthesis and occurrence of cyanides before disseminating several examples of recent analytical protocols tailored towards the detection of cyanides within a range of media