Hydrophobic POM Electrocatalyst Achieves Low Voltage “Charge” in Zn‐Air Battery Coupled with Bisphenol A Degradation

Abstract

Zn‐air batteriesare a perspective power source for grid‐storage. But, after they are discharged at1.1 to 1.2 V, large overpotential is required for their charging (usually 2.5 V). This is due to a sluggish oxygen evolution reaction (OER). Incorporating organic pollutants into the cathode electrolyte is a feasible strategy for lowering the required charging potential. In the discharge process, the related oxygen reduction reaction, hydrophobic electrocatalysts are more popular than hydrophilic ones. Here, a hydrophobic bifunctional polyoxometalate electrocatalyst is synthesized by precise structural design. It shows excellent activities in both bisphenol A degradation and oxygen reduction reactions. In bisphenol A containing electrolyte, to achieve 100 mA ⋅ cm−2, its potential is only 1.32 V, which is 0.34 V lower than oxygen evolution reaction. In the oxygen reduction reaction, this electrocatalyst follows the four‐electron mechanism. In both bisphenol A degradation and oxygen reduction reactions, it shows excellent stability. With this electrocatalyst as cathode material and bisphenol A containing KOH as electrolyte, a Zn‐air battery was assembled. When “charged” at 85 mA ⋅ cm−2, it only requires 1.98 V. Peak power density of this Zn‐air battery reaches 120.5 mW ⋅ cm−2. More importantly, in the “charge” process, bisphenol A is degraded, which achieves energy saving and pollutant removal simultaneously in one Zn‐air battery.

High Performance Bifunctional Electrocatalysts Designed Based on Transition‐Metal Sulfides for Rechargeable Zn–Air Batteries

“…The group of Xu synthesized a hydrophobic bifunctional polyoxymetalate electrocatalyst with good ORR activity. [98] The ZABs assembled with this electrocatalyst as the cathode material can achieve a peak power density of 120.5 mW•cm À 2 . Therefore, designing the interface or surface structure is an effective way to improve the catalytic performance, because it can adjust the electron transfer and surface binding energy between the twophase interface.…”

“…OER requires a hydrophilic/aerophobic interface, while ORR requires a hydrophobic/aerophilic interface. The group of Xu synthesized a hydrophobic bifunctional polyoxymetalate electrocatalyst with good ORR activity [98] . The ZABs assembled with this electrocatalyst as the cathode material can achieve a peak power density of 120.5 mW⋅cm −2 .…”

Transition Metal-Based Polyoxometalates for Oxygen Electrode Bifunctional Electrocatalysis

“…Polyoxometalates (POMs) are polyatomic transition metal oxyanions with a tridimensional framework, emerging as promising electrocatalysts owing to their high thermal stability, tunable structure, and mechanical and redox properties [7,8]. Thus, they have found applications as electrocatalysts for ORR [9][10][11][12] and OER [11,[13][14][15] in fuel cells, batteries [9,11,13,16], and electrolytic cells [14]. Adjusting the electrochemical and mechanical properties of POMs can be accomplished by varying the composition of their framework by introducing different metal redox centers [17,18] or incorporating the whole POM structure into porous materials or conductive substrates [7].…”

Two new manganese-based phosphomolybdate compounds as electrochemical sensors for the highly sensitive trace determination of heavy metal Cr(vi) ions

“…30–32 All Mo atoms in {P 4 Mo 6 } have high-reduction states, showing obvious redox properties in the electrochemical process. 28,33–36 Recently, {P 4 Mo 6 }-based compounds have been widely used in the field of electrochemistry with good results, such as electrocatalytic reduction of Cr( vi ), 6,37,38 electrocatalytic hydrogen, 39,40 oxygen production, 41 battery, 42 and proton conduction. 34,43,44 Han and his co-workers used electrochemical sensing technology to detect Cr( vi ) based on {P 4 Mo 6 }-containing compounds.…”