Selective electrocatalytic hydrogenation of nitrobenzene over copper-platinum alloying catalysts: Experimental and theoretical studies

Fig. 1. (a) Schematic illustration of the synthetic process of CuxPty anoparticles. (b) TEM image of Cu3Pt/C. (c) HRTEM image of Cu3Pt/C and selected area electron diffraction (SAED) pattern (inset). (d) HAADF-STEM and element mapping images. (e) XRD patterns of as-synthesized Cu5Pt/C, Cu3Pt/C, CuPt/C, Pt/C and Cu/C. (f) Pt 4f XPS spectra of Cu5Pt/C, Cu3Pt/C, CuPt/C and Pt/C. (g) Cu 2p XPS spectra of Cu5Pt/C, Cu3Pt/C, CuPt/C and Cu/C.Fig. 2. All polarization curves were without iR-compensation corrected. LSV curves of Cu/C, Pt/C, CuPt/C, Cu3Pt and Cu5Pt catalysts in 1.0 M KOH (a) without Ph-NO2 and (b) with 5.0 mM Ph-NO2. (c) The half-wave potential (E1 and E2) of Cu/C, Pt/C, CuPt/C, Cu3Pt and Cu5Pt catalysts. (d) ECSA-normalized current densities.Fig. 3. (a) The j-E plots of Ph-NO2 reduction on Cu3Pt/C at different rotation rates. (b) The Kout´ecky-Levich (K-L) plots of Ph-NO2 reduction on Cu3Pt/C at different applied potentials. (c) The conversion and product selectivity of Ph-NO2 reduction over Cu3Pt/C catalyst at different applied potentials. (d) The product selectivity of Ph-NO2 reduction over Cu3Pt/C catalyst at different pH solutions and different applied potential.Fig. 4. (a) Schematic illustration for the home-made electrochemical microflow cell (EMFC). (b) The i-t curves of Ph-NO2 reduction over Cu3Pt/C using the home-made EMFC. (c) Time-dependent conversion and yield of Ph-NO2 reduction over Cu3Pt/C in EMFC device at 0.3 V (vs. RHE). (d) Time-dependent conversion and yield of Ph-NO2 reduction over Cu3Pt/C in EMFC device at -0.2 V (vs. RHE).Fig. 5. (a) Top view and side view of parallel adsorption of nitrobenzene on Cu3Pt(111). (b) DOS of Cu(111) and Cu3Pt(111).(c) Density of states of the C 2p, O 2p, N 2p, Pt-5d, and Cu-5d orbitals with Cu3Pt(111). (d) The calculated Gibbs free energy of the direct deoxygenation route (Blue line) and the successive deoxygenation and re-hydrogenation route (SDR route) (Red line) at U = 0 and pH = 14. (e) The selectivity of the Cu(111), Pt(111), and Cu3Pt(111) catalyst for the Ph-NO2 reduction. (f) The Gibbs free energy in the SDR route of Cu3Pt(111) under different pH at U = 0. Red, pink, blue, gray, light blue, and brown spheres correspond to oxygen, hydrogen, copper, platinum, nitrogen and carbon atoms, respectively.