Free-electrodeposited anodic stripping voltammetry sensing of Cu based on Ti.sub.3C.sub.2T.sub.x MXene/carbon black

A proof-of-principle concept for free-electrodeposited anodic stripping voltammetry (ASV) sensing of Cu.sup.2+ is proposed by using Ti.sub.3C.sub.2T.sub.x MXene/carbon black (Ti.sub.3C.sub.2T.sub.x@CB) nanohybrids as electrode materials. Owing to the high adsorption and reduction capability of Ti.sub.3C.sub.2T.sub.x towards Cu.sup.2+, Ti.sub.3C.sub.2T.sub.x MXene enables Cu.sup.2+ to be immobilized and self-reduced directly to form Cu.sup.0 on the Ti.sub.3C.sub.2T.sub.x@CB electrode surface. As a result an oxidation peak current appears from the re-oxidation of Cu.sup.0 via differential pulse voltammetry. Carbon black (CB) was introduced to prevent Ti.sub.3C.sub.2T.sub.x Mxene aggregation and improve the related electron transfer as well as enhance their surface area. After optimizing various conditions, a considerable low limit of detection (4.6 nM) and a wide linear range (0.01-15.0 [mu]M) for Cu.sup.2+ were achieved at the working potential from - 0.3 V to 0.0 V (vs SCE). Relative standard deviation (RSD) of eight individual Ti.sub.3C.sub.2T.sub.x@CB electrodes is 3.72%, and the recoveries from tap water sample and lake water sample were in the ranges of 97.0-108% and 104-107%, respectively. Graphical abstract