Phase-Selective Cation-Exchange Chemistry in Sulfide Nanowire Systems

Abstract

As a cation-deficient, p-type semiconductor, copper sulfide (Cu 2−x S) shows promise for applications such as photovoltaics, memristors, and plasmonics. However, these applications demand precise tuning of the crystal phase as well as the stoichiometry of Cu 2−x S, an ongoing challenge in the synthesis of Cu 2−x S materials for a specific application. Here, a detailed transformation diagram of cation-exchange (CE) chemistry from cadmium sulfide (CdS) into Cu 2−x S nanowires (NWs) is reported. By varying the reaction time and the reactants' concentration ratio, the progression of the CE process was captured, and tunable crystal phases of the Cu 2−x S were achieved. It is proposed that the evolution of Cu 2−x S phases in a NW system is dependent on both kinetic and thermodynamic factors. The reported data demonstrate that CE can be used to precisely control the structure, composition, and crystal phases of NWs, and such control may be generalized to other material systems for a variety of practical applications.

Tunable and Specific Formation of C@NiCoP Peapods with Enhanced HER Activity and Lithium Storage Performance

“…[19,21,35] Furthermore, the spectrum of P2 pa lso presentsapeak with ah igh BE of 133.6 eV,w hich could be attributed to PO 4 3À or P 2 O 5 caused by oxidationd ue to air contact. [19,21,35] Similarly,r esults are obtained from the XPS spectra of Co 2 Pb ulks, as shown in Figure 5b.O bviously,t he peaks of Co 2 Pb ulk correspond to those of previously reported purephased Co 2 P. [34][35][36] The HER activities of C@Ni 2 P, C@Ni 1.5 Co 0.5 P, and C@NiCoP and Co 2 Pb ulks are measured in 0.5 m H 2 SO 4 using at ypical threeelectrode setup. Similarm easurements for Pt/C electrodes are also performed.…”

“…[24,32] Recently,anion-exchange has emerged as apowerful pathway to controlt he phases of late-transition-metal compounds because it preserves the anionic framework. [33][34] In this paper,t he NiCoP nanoparticles encapsulated in the carbon tubes obtained from ah ydrothermal anion-exchange method followed by annealing under aH 2 atmosphere are well dispersedw ith slight agglomeration, which implies the high sta- www.chemeurj.org bility of the peapodlike nanostructured products for HER or LIBs. The specific surface area of the peapodlike nanocomposites are measuredb yn itrogen adsorption/desorption isotherms and are estimated to be as high as 110m 2 g À1 using the Brunauer-Emmett-Teller (BET) method ( Figure 2d).…”

Electrically driven cation exchange for in situ fabrication of individual nanostructures

“…1g, the SAED pattern (Fig. 1h) shows two sets of diffraction spots from WZ CdS and low chalcocite (LC) Cu 2 S. As mentioned in previous works, copper sulfide containing both sub-stoichiometric djurleite (Cu 1.93–1.97 S) and stoichiometric LC (Cu 2 S) phases can be formed from CdS315. It has been shown that djurleite transforms to LC by elimination of a copper vacancy with electron reduction or any other process315.…”

“…Cation exchange (CE) reactions, in which one type of cation ligated within an intact anion sublattice are substituted by another kind of cation, have been regarded as a particularly powerful approach for the growth of heterogeneous structures that are not easily obtained using direct synthesis techniques123. The feasibility and the rates of CE processes depend both on the solubility product constant and the nature of the intervening activation barriers during reaction45.…”

Excited-State Dynamics in Colloidal Semiconductor Nanocrystals

“…Another important consequence of the large contribution of surface atoms to the properties of NCs is the enhancement of the solid-state diffusion rates. This has made it possible to use nanoscale cation exchange and/or controlled interdiffusion as post-synthetic strategies to tailor the properties of NCs and hetero-NCs while preserving their size, shape, and heterostructure, by tuning their composition and/or elemental distribution profile [82,[104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120][121][122]. These techniques have also been recently used to achieve doping of semiconductor NCs [96,97,100].…”