Facile synthesis of flower like copper oxide and their application to hydrogen peroxide and nitrite sensing

<p>Abstract</p> <p>Background</p> <p>The detection of hydrogen peroxide (H₂O₂) and nitrite ion (<inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1752-153X-5-75-i1"><m:mrow><m:msubsup><m:mrow><m:mstyle class="text"><m:mtext>NO</m:mtext></m:mstyle></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow><m:mrow><m:mo class="MathClass-bin">-</m:mo></m:mrow></m:msubsup></m:mrow></m:math></inline-formula>) is of great important in various fields including clinic, food, pharmaceutical and environmental analyses. Compared with many methods that have been developed for the determination of them, the electrochemical detection method has attracted much attention. In recent years, with the development of nanotechnology, many kinds of micro/nano-scale materials have been used in the construction of electrochemical biosensors because of their unique and particular properties. Among these catalysts, copper oxide (CuO), as a well known p-type semiconductor, has gained increasing attention not only for its unique properties but also for its applications in many fields such as gas sensors, photocatalyst and electrochemistry sensors. Continuing our previous investigations on transition-metal oxide including cuprous oxide and α-Fe₂O₃modified electrode, in the present paper we examine the electrochemical and electrocatalytical behavior of flower like copper oxide modified glass carbon electrodes (CuO/GCE).</p> <p>Results</p> <p>Flower like copper oxide (CuO) composed of many nanoflake was synthesized by a simple hydrothermal reaction and characterized using field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). CuO modified glass carbon electrode (CuO/GCE) was fabricated and characterized electrochemically. A highly sensitive method for the rapid amperometric detection of hydrogen peroxide (H₂O₂) and nitrite (<inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1752-153X-5-75-i1"><m:mrow><m:msubsup><m:mrow><m:mstyle class="text"><m:mtext>NO</m:mtext></m:mstyle></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow><m:mrow><m:mo class="MathClass-bin">-</m:mo></m:mrow></m:msubsup></m:mrow></m:math></inline-formula>) was reported.</p> <p>Conclusions</p> <p>Due to the large specific surface area and inner characteristic of the flower like CuO, the resulting electrode show excellent electrocatalytic reduction for H₂O₂and oxidation of <inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1752-153X-5-75-i1"><m:mrow><m:msubsup><m:mrow><m:mstyle class="text"><m:mtext>NO</m:mtext></m:mstyle></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow><m:mrow><m:mo class="MathClass-bin">-</m:mo></m:mrow></m:msubsup></m:mrow></m:math></inline-formula>. Its sensitivity, low detection limit, fast response time and simplicity are satisfactory. Furthermore, this synthetic approach can also be applied for the synthesis of other inorganic oxides with improved performances and they can also be extended to construct other micro/nano-structured functional surfaces.</p

Silver nanoparticle assemblies supported on glassy-carbon electrodes for the electro-analytical detection of hydrogen peroxide.

Electrochemical detection of hydrogen peroxide using an edge-plane pyrolytic-graphite electrode (EPPG), a glassy carbon (GC) electrode, and a silver nanoparticle-modified GC electrode is reported. It is shown, in phosphate buffer (0.05 mol L(-1), pH 7.4), that hydrogen peroxide cannot be detected directly on either the EPPG or GC electrodes. However, reduction can be facilitated by modification of the glassy-carbon surface with nanosized silver assemblies. The optimum conditions for modification of the GC electrode with silver nanoparticles were found to be deposition for 1 min at -0.5 V vs. Ag from 5 mmol L(-1) AgNO3/0.1 mol L(-1) TBAP/MeCN, followed by stripping for 2 min at +0.5 V vs. Ag in the same solution. A wave, due to the reduction of hydrogen peroxide on the silver nanoparticles is observed at -0.68 V vs. SCE. The limit of detection for this modified nanosilver electrode was 2.0 x 10(-6) mol L(-1) for hydrogen peroxide in phosphate buffer (0.05 mol L(-1), pH 7.4) with a sensitivity which is five times higher than that observed at a silver macro-electrode. Also observed is a shoulder on the voltammetric wave corresponding to the reduction of oxygen, which is produced by silver-catalysed chemical decomposition of hydrogen peroxide to water and oxygen then oxygen reduction at the surface of the glassy-carbon electrode