Efficiently Enhancing Electrocatalytic Activity of α-MnO2 Nanorods/N-Doped Ketjenblack Carbon for Oxygen Reduction Reaction and Oxygen Evolution Reaction Using Facile Regulated Hydrothermal Treatment

Abstract

Scalable, low-cost and highly efficient catalysis of oxygen electrocatalytic reactions (ORR/OER) are required for the rapid development of clean and renewable energy conversion/storage technologies. Herein, two types of α-MnO 2 nanorods were prepared under hydrothermal treatment at 150 • C for 0.5 h (MnO 2 -150-0.5) or 120 • C for 12 h (MnO 2 -120-12), then supported on N-doped ketjenblack carbon (N-KB) as bi-functional ORR/OER catalysts. Their electrocatalytic activities toward ORR and OER were investigated systematically. As a result, MnO 2 -150-0.5/N-KB displays superior ORR catalytic activity, with much more positive half-wave potential and much larger limiting current density (0.76 V and 6.0 mA cm −2 ), comparable to those of 20 wt. % Pt/C (0.82 V and 5.10 mA cm −2 ). MnO 2 -150-0.5/N-KB also shows high electron transfer number (3.86~3.97) and low yield of peroxides (1-7%) during ORR process in the whole potential range of 0-1.0 V (vs. RHE). Meanwhile, the MnO 2 -150-0.5/N-KB also exhibits better OER activity with low overpotential, comparable to IrO 2 /N-KB. The excellent electrocatalytic activity of MnO 2 -150-0.5/N-KB can be attributed to the synergistic effect, relatively smaller size, higher amount of Mn 3+ , and low charge transfer resistance. This work offers a new strategy for scalable preparation of more efficient and cost-effective α-MnO 2 bi-functional oxygen catalysts.

Hydrothermally Carbonized Waste Biomass as Electrocatalyst Support for α-MnO2 in Oxygen Reduction Reaction

“…Furthermore, the figures also suggest that the incorporation of α-MnO 2 in the activated carbon improved the ORR performance. This is observed also when doped carbon materials were added to the active electrocatalyst in other studies [10,15,18]. Among the samples that were analyzed, hydrochar and activated carbon produced from HTC at 250 • C for 12 h showed the highest performance, which is consistent with the CV results.…”

“…On the other hand, it can be concluded that RHAC-and SDAC-supported α-MnO 2 exhibits ORR that proceeds both in 2-e − and 4-e − pathways, which resulted in an electron transfer number approaching three (3). In other studies [10,19,58], the electron pathway is influenced both by the individual ORR mechanism of the carbon support and the electrocatalyst. For such materials, ORR proceeds both in the composites, hence a mixed behavior can be expected.…”

Determination of Uric Acid in Co-Presence of Dopamine and Ascorbic Acid Using Cuprous Oxide Nanoparticle-Functionalized Graphene Decorated Glassy Carbon Electrode

“…Scheme 1. The reaction mechanism of UA.In the past few years, transition metals and metal oxides have received increasing attention in many fields, such as sensors and electrocatalysis, due to their unique sensing performance and superior electrocatalytic activity [9,11,23,24]. Among these metal oxides, cuprous oxide (Cu2O) is a new type of p-type semiconductor with a narrow band gap, which can also be easily excited by visible light.…”

Abnormal Anionic Porphyrin Sensing Effect for HER2 Gene Related DNA Detection via Impedance Difference between MWCNTs and Single-Stranded DNA or Double-Stranded DNA

“…All DNA sensors were immersed into an electrochemical cell in 0.05 M Tris-HCl buffer solution (pH 7.40) containing 0.005 M [Fe(CN) 6 ] 3−/4− and 0.20 M KCl. Electrochemical impedance electrochemical impedance spectroscopy (EIS) is a nondestructive technique, which has been widely used in the biopotential sensors [ 39 ], electrocatalysis [ 40 , 41 ] and electrochemical sensors [ 31 ]. Herein, EIS was employed for the detection of target DNA.…”