Co3O4 Supported on Graphene-like Carbon by One-Step Calcination of Cobalt Phthalocyanine for Efficient Oxygen Reduction Reaction under Alkaline Medium

Abstract

Exploiting cost-effective and durable non-platinum electrocatalysts for oxygen reduction reaction (ORR) is of great significance for the development of abundant renewable energy conversion and storage technologies. Herein, a series of Co3O4 supported on graphene-like carbon (Co3O4/C) samples were firstly effectively synthesized by one-step calcination of cobalt phthalocyanine and their electrocatalytic performances were measured for ORR under an alkaline medium. By systematically adjusting the calcination temperature of cobalt phthalocyanine, we found that the material pyrolyzed at 750 °C (Co3O4/C−750) shows the best ORR electrocatalytic performance (half-wave potentials of 0.77 V (vs. RHE) in 0.1 M KOH) among all the control samples. Moreover, it displays better stability and superior methanol tolerance than commercial 20% Pt/C. The further electrochemical test results reveal that the process is close in characteristics to the four-electron ORR process on Co3O4/C−750. In addition, Co3O4/C−750 applied in the zinc–air battery presents 1.34 V of open circuit potential. Based on all the characterizations, the enhanced electrocatalytic performances of Co3O4/C−750 composite should be ascribed to the synergistic effect between Co3O4 and the graphene-like carbon layer structure produced by pyrolysis of cobalt phthalocyanine, as well as its high specific surface area.

Improving Cycle Life of Zinc–Air Batteries with Calcium Ion Additive in Electrolyte or Separator

“…It could be demonstrated that K 2 CO 3 and CaCO 3 were generated during charge–discharge cycling [ 7 , 8 , 11 , 26 , 27 , 28 , 37 ]. Considering the voltage loss (i.e., iR drop) caused by the electrolyte solution between the working electrode and the reference electrode, corrected ORR and OER performance of the cycled air cathode by iR compensation was investigated in Figure 8 , and both of them were significantly decreased after cycling, and its performance with a modified electrolyte deteriorated more than the one with a modified separator [ 8 , 11 , 26 , 27 , 28 , 29 , 30 , 49 , 50 ]. After cycling, the micropores of the air cathode could easily be blocked by the generated lamellar K 2 CO 3 , hindering the diffusion of O 2 through the air cathode to participate in ORR and OER reaction, resulting in the remarkable decrease in ORR and OER performance of air cathode.…”

Efficient electrocatalytic oxygen reduction reaction of thermally optimized carbon black supported zeolitic imidazolate framework nanocrystals under low-temperature

“…Pre-synthesized porous networks, such as metal-organic frameworks (MOFs) are oen utilised precursors with the choice of enriched metal centres and ligand/linker carbon network with functional heteroatom groups, which can enhance the electrophilicity and heterogeneity of the metalcarbon network and thus promote the adsorption/desorption of reactants/intermediates during the catalytic process. 1,[3][4][5][6][7][8][9][10][11][12][13][14][15]18,[22][23][24] MOFs, such as ZIFs comprising highly accessible porosity and surface area along with metal and nitrogen elements have delivered superior functional electrocatalysts in the form of metal-nitrogen-carbon (usually denoted as M-N-C) or metal/ metal-oxide nanoparticle embedded N-C matrix (MO x -N-C or M@MO x -N-C). For example, the carbothermal modulation of Co metal based MOFs/ZIFs can generate Co-N-C or Co@Co 3 O 4 and/or Co@CoO x nanoparticles embedded N-C materials.…”

“…For example, the carbothermal modulation of Co metal based MOFs/ZIFs can generate Co-N-C or Co@Co 3 O 4 and/or Co@CoO x nanoparticles embedded N-C materials. [3][4][5]7,[10][11][12][13]15,18,22,23,[27][28][29][30][31][32][33][34][35][36] However, the high-temperature carbothermal modication process, commonly carried out between 800-1000 °C for a few hours, along with signicant ligand volatility and metal-centres agglomeration, limits their full potential of scalable synthesis and efficient electrocatalytic performance. Attempts to use low-temperature carbothermal synthesis resulted in unsatisfactory electrochemical performance due to poor electrical conductivity of carbon network.…”

“…Attempts to use low-temperature carbothermal synthesis resulted in unsatisfactory electrochemical performance due to poor electrical conductivity of carbon network. 4,5,11,12,22,23 Pre-fabricated conducting carbon supports have been used to support polymer, MOF or ZIF structures and exploited for their electrocatalytic activities under low carbothermal modulation. For example, reduced graphene-oxide (rGO), 4,15,29,31 carbon nanotube (CNT), 9,18,21,27 carbon cloth/paper (CC/CP), carbon nanober (CNF), 2,10,13,19,32,33 small metal-coordinated molecules/polymers or MOFs-derived carbon (MDC) templated and/or ordered mesoporous carbon (OMC) [2][3][4]6,7,9,11,16,22,23,[27][28][29][30][31][32][33][34][35][36] have been used.…”

“…4,5,11,12,22,23 Pre-fabricated conducting carbon supports have been used to support polymer, MOF or ZIF structures and exploited for their electrocatalytic activities under low carbothermal modulation. For example, reduced graphene-oxide (rGO), 4,15,29,31 carbon nanotube (CNT), 9,18,21,27 carbon cloth/paper (CC/CP), carbon nanober (CNF), 2,10,13,19,32,33 small metal-coordinated molecules/polymers or MOFs-derived carbon (MDC) templated and/or ordered mesoporous carbon (OMC) [2][3][4]6,7,9,11,16,22,23,[27][28][29][30][31][32][33][34][35][36] have been used. However, such pre-synthesized carbon supports offer no commercial/scalable benets as they require complex and prolonged chemical modications.…”