Volume 4, Issue 1, Pages 106-123 (January 2018) N-Doped Graphitized Carbon Nanohorns as a Forefront Electrocatalyst in Highly Selective O2 Reduction to H2O2  Daniel Iglesias, Angela Giuliani, Michele Melchionna, Silvia Marchesan, Alejandro Criado, Lucia Nasi, Manuela Bevilacqua, Claudio Tavagnacco, Francesco Vizza, Maurizio Prato, Paolo Fornasiero  Chem  Volume 4, Issue 1, Pages 106-123 (January 2018) DOI: 10.1016/j.chempr.2017.10.013 Copyright © 2017 Elsevier Inc. Terms and Conditions

Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 1 Scheme of the Synthesis and Relative TEM Analysis (Top) Scheme of the synthetic protocol to obtain g-N-CNHs. (Bottom) TEM images of the nanostructured material at each stage of the synthesis. Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 2 Further Microscopy Investigation Confirming Composition and Structure EDX mapping of the three elements C, N, and O and HAADF-STEM of ox-CNHs@PDA (top) and g-N-CNHs (bottom). Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 3 Physical Characterization of the CNH-Based Materials (A) TGA under N2 flow. (B) TGA under air flow. (C) Raman of the samples at each synthetic stage. (D) XPS analysis of g-N-CNHs in the C1s, O1s, and N1s BE ranges. Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 4 Analysis of the Electrochemical Properties through CV Experiments (A) CVs obtained on glassy carbon electrode (GCE) modified with ox-CNHs (black line), ox-CNHs@PDA (red line), and g-N-CNHs (green line) in 0.10 M PBS (pH 7.4) under N2. (B–D) Multicycle (up to 20 cycles) CVs obtained on GCE modified with ox-CNHs (B), ox-CNHs@PDA (C), and g-N-CNHs (D) in 0.10 M PBS (pH 7.40) under N2. Scan rate, 0.05 V s−1. Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 5 Electrochemical Analysis of the O2 Reduction through Cyclic Voltammetry Background-subtracted CVs obtained on GCE modified with g-N-CNHs at pH 1.0 in 0.1 M H2SO4 (red line), at pH 7.4 in 0.10 M phosphate buffer solution (green line), and at pH 13.0 in 0.1 M NaOH (blue line) under pure O2. Scan rate, 0.05 V s−1. Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 6 Study of the Variation of FE in Relation to pH and Applied Potential and Evaluation of the Stability over Long-Term Electrolysis Experiments (A–C) FE% of H2O2 produced after 1 hr of electrolysis at three different fixed potentials (for each pH value) using a g-N-CNH modified electrode at pH 1.0 (A), pH 7.4 (B), pH 13.0 (C) at three different potential values for each medium. (D) Plots of FE percentage versus time. (E) A stability test at pH 1.0, 7.4, and 13.0 over 24 hr was carried out with a three-electrode cell comprising a working electrode made of g-N-CNH-modified glassy carbon, a counter electrode made of Pt net separated from the bulk solution by a porous membrane, and a reference Ag/AgCl electrode. Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 7 Tafel Analysis of the Catalyst under Different pH Regimes Tafel plots of logIK versus E (V) for the ORR on the g-N-CNH electrode in oxygen-saturated solution at pH 1.0 (red line), at pH 7.4 (green line), and at pH 13.0 (blue line) under O2. Scan rate, 0.05 V s−1; RDE rotation rate, 1,200 rpm. Chem 2018 4, 106-123DOI: (10.1016/j.chempr.2017.10.013) Copyright © 2017 Elsevier Inc. Terms and Conditions