Chromium nitrate

All reagents were analytical grade and used without further purification. Chromium nitrate (Cr(NO₃)₃·9H₂O, 99 wt%), stannic chloride (SnCl₄·5H₂O, 99 wt%), hydrofluoric acid (HF, 49%), anhydrous ethanol (99.5 wt%), pyridine (99.5 wt%), and octane (99.5 wt%) were purchased from Sinopharm Chemical Reagent Co. Ltd., China. Terephthalic acid (H₂BDC, 99 wt%) was supplied by Alfa Aesar China Co., Ltd. (Tianjin, China).

Terephthalic acid (99%), trimesic acid (99%), cystamine hydrochloride, and 2,3,4,5,6-pentafluorobenzyl bromide (99%) were purchased from J&K Scientific Ltd. (Beijing, China). Chromium nitrate, copper(II) acetate, and L-glutamic acid were bought from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China). Carbonic anhydrase (CA, bovine red blood cell), formate dehydrogenase (FateDH, lyophilized), and glutamate dehydrogenase (GDH, bovine liver) were provided by Sigma-Aldrich (St. Louis, MO, USA). Nicotinamide adenine quinone dinucleotide (NADH, 98%) was obtained from Aladdin Biotechnology Co., Ltd. (Shanghai, China). CO₂ (>99%) and ¹³CO₂ (>99%) were purchased from Beijing Ruyuan Ruquan Technology Co., Ltd. (Beijing, China). All other chemicals were obtained from Beijing Chemical Factory (Beijing, China). Double-distilled water was used in all experiments.

Linter Cellulose (M_w = 8 × 10⁴) was provided by Hubei Chemical Fiber Group Co. Ltd. Epichlorohydrin (ECH), sodium hydroxide (NaOH), urea, copper sulfate (CuSO₄), mercury nitrate (Hg(NO₃)₂), silver nitrate (AgNO₃), manganese nitrate [Mn(NO₃)₂], chromium nitrate [Cr(NO₃)₃], lead nitrate [Pb(NO₃)₂], copper chloride (CuCl₂), ferric chloride (FeCl₃), calcium chloride (CaCl₂), nickel chloride (NiCl₂), cobalt chloride (CoCl₂), zinc chloride (ZnCl₂), and magnesium chloride (MgCl₂) were purchased from Sinopharm Group, Shanghai, China. All reagents were of analytical reagent grade, and all chemicals were used without further purification.