Chromium chloride hexahydrate

Sodium hydroxide (NaOH), hydrochloric acid (HCl) aluminium sulphate (Al₂(SO₄)₃·18H₂O), chromium chloride hexahydrate (CrCl₃·6H₂O), copper sulphate pentahydrate (CuSO₄·5H₂O), 10-hydroxybenzo[h]quinoline (C₁₃H₉NO, the structure is shown in scheme 1a, abbreviated as HBQ) and silica gel (30 wt% Aldrich), were purchased from Sinopharm Chemical Reagent Co., Ltd. All chemicals were of analytical grade and used without any further purification. Scheme 2 schematically illustrates the synthetic process of HBQ-M-mags (M = Al, Cr and Cu) in the interlayer spaces of mags and the detailed process is described in the following sections.
Scheme 2.

A schematic illustration of preparation of M(HBQ)_n (M = Al, Cr, Cu) in the interlayer space of mags and proposed structures of mag, H-mag, M-mag and HBQ-M-mag.

Iron chloride hexahydrate (FeCl₃·6H₂O), nickel chloride hexahydrate (NiCl₂·6H₂O), cobalt chloride hexahydrate (CoCl₂·6H₂O), chromium chloride hexahydrate (CrCl₃·6H₂O), sodium borohydride (NaBH₄) and ethanol were purchased from Sinopharm Chemical Reagent Co., Ltd. Potassium hydroxide (KOH, electronic grade, 99.999% metals basis, except sodium) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Ruthenium dioxide (99.9% trace metals basis) and Nafion®117 solution (5%) were purchased from Sigma-Aldrich. Carbon black (ECP600JD, Ketjenblack®) for electrochemical measurements was obtained from Suzhou Sinero Technology Co., Ltd. and graphite powder (XF009 7782-42-5) for XAS characterization was obtained from XFNANO Materials Tech Co., Ltd. All chemicals can be used without further purification.