Cobalt‐Doped Tungsten Sulfides as Stable and Efficient Air Electrodes for Rechargeable Zinc‐Air Batteries

Abstract

Stable and efficient air electrode are significantly important for the industrial applications of rechargeable zinc‐air batteries (ZABs). In this work, we introduce approximately 1 at % cobalt to tungsten sulfides nanosheets (Co−WS2) to create a bifunctional electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). A boosted ORR activity with half‐wave potential of 840 mV vs. RHE is achieved for Co−WS2 compared to that of WS2 (776 mV vs. RHE). Meanwhile, the overpotential for delivering 10 mA cm−2 in OER catalysis is decreased from 492 to 303 mV after doping with Co atoms. The excellent ORR and OER activities are ascribed to the presence of Co2+ and Co3+ species in Co−WS2, enabling OOH* intermediate formation and strong binding ability to O2, respectively. The assembled liquid rechargeable ZAB from Co−WS2 exhibits a threefold higher power density than commercial Pt/C−IrO2; moreover, a stable discharge‐charge performance (100 cycles) is recorded. Finally, the fabricated all‐solid‐sate ZAB exhibits a reasonably high power density of 58 mW cm−2 and good stability, implying the potential application of Co−WS2 as an air electrode for rechargeable ZABs.

Tuning the intrinsic catalytic activities of oxygen-evolution catalysts by doping: a comprehensive review

“…Like in metal oxides and hydroxides, Fe doping is evident in significantly improving the OER activity of TM sulfides. 139,140 147 257 mV @ 50 mA cm -2 81 24 h @ 0.6 V vs Ag/AgCl 1 M KOH Co-doped WS2 148 303 mV @ 10 mA cm -2 79 -1 M KOH CoFeS/CNT-P 1000 149 309 mV @ 100 mA cm -2 47 12 h @ 20 mA cm -2 1 M KOH Fe-doped CoS 141 290 mV @ 10 mA cm -2 52.6 10 h @ 10 mA cm -2 1 M KOH Fe-doped Co9S8 142 270 mV @ 10 mA cm -2 70 10 h @ 270 mV 1 M KOH Fe-doped NiS2 143 231 mV @ 100 mA cm -2 43 15 h @ 20 mA cm -2 1 M KOH Fe-doped Ni3S2 144 223 mV @ 200 mA cm -2 55.7 14 h @ 223 mV 1 M KOH Fe-doped Ni3S2/NF 139 249 mV @ 100 mA cm -2 42 20 h @ 270 mV 1 M KOH Fe2.1% doped Ni3S2/NF 140 213 mV @ 100 mA cm -2 33.2 -1 M KOH Fe-doped H-CoMoS 145 282 mV @ 10 mA cm -2 58 1 M KOH Ni1.29Co1.49Mn0.22S4 150 348 mV @ 10 mA cm -2 65 40,000 s @ 10 mA cm -2 1 M KOH N-doped Co9S8/G 151 409 mV @ 10 mA cm -2 82.7 -0.1 M KOH Ni-doped FeS 152 228 mV @ 10 mA cm -2 53 10 h @ 1.47 V vs RHE 1 M KOH N2-NiS2-500 153 270 mV @ 10 mA cm -2 40 h @ 270 mV 1 M KOH (N-Ni3S2@C)/NF 154 310 mV @ 100 mA cm -2 75 20 h @ 1.70 V vs RHE 1 M KOH N-doped NiS/NiS2 155 270 mV @ 10 mA cm -2 99 20 h @ 270 mV 1 M KOH P-doped Co-Ni-S Nanosheets 156 296 mV @ 100 mA cm -2 61.1 16 h @ 10 mA cm -2 1 M KOH P-Ni3S2/NF 157 256 mV @ 10 mA cm -2 30 30 h @ 1.525 V vs RHE 1 M KOH P-Ni3S2/NF 158 306 mV @ 100 mA cm -2 99 10 h @ 1.54 V vs RHE 1 M KOH (P-(Ni,Fe)3S2/NF 159 196 mV @ 10 mA cm -2 30 15 h @ 295 mV 1 M KOH Zn-doped Ni3S2 160 330 mV @ 100 mA cm -2 87 20 h @ 300 mV 1 M KOH Metal selenides Fe-doped CoSe2/NF 161 256 mV @ 100 mA cm -2 35.6 10 h @ 231 mV 1 M KOH Ag-doped CoSe2 nanobelts 162 320 mV @ 10 mA cm -2 56 -0.1 M KOH B-doped Fe5Co4Ni20Se36 163 279.8 mV @ 10 mA cm -2 59.5 10 h @ 10 mA cm -2 1 M KOH Co-doped NiSe 164 380 mV @ 100 mA cm -2 111 >10 h @ 320mV 1 M KOH Co-doped Nickel selenide 165 275 mV @ 30 mA cm -2 63 24 h @ 1.5 V vs RHE 1 M KOH Co0.75Fe0.25(S0.2Se0.8)2 166 293 mV @ 10 mA cm -2 77 -1 M KOH Cu-14-Co3Se4/GC…”

“…Open Fe-doped NiSe2 171 231 mV @ 10 mA cm -2 83 20 h @ mA cm -2 1 M KOH Fe-doped Ni3Se4 172 225 mV @ 10 mA cm -2 41 26 h @ 10 mA cm -2 1 M KOH Fe-doped Ni3Se2 173 225 mV @ 10 mA cm -2 35.3 12 h @ 20 mA cm -2 1 M KOH Ni1.12Fe0.49Se2 174 227 mV @ 10 mA cm -2 37.9 10 h @ 10 mA cm -2 1 M KOH Ni0.04Fe0.16 Co0.8Se2 175 230 mV @ 10 mA cm -2 39 15 h @ 1.5 V vs RHE 1 M KOH VSe-Ni0.70Fe0.30Se2 176 210 mV @ 10 mA cm -2 61 20 h @ 10 mA cm -2 1 M KOH Zn-doped CoSe2 177 286 mV @ 10 mA cm -2 37 24 h @ 10, 20, 50 mA cm -2 1 M KOH In addition to the Fe inclusion, doping of other metals such as Ni, 152,178 Co, 148 Mn, 150 Zn, 160 Ce, 147 and Al 146 are also found to be enhancing the OER activity of metal sulfides. For instance, Lin et al fabricated…”

“…Still, it promotes the OER activity by regulating the active sites and chemical states on the surface of Ni 3 S 2 . Yang et al significantly enhanced the electrocatalytic ability of WS 2 byincorporating nearly 1% Co into its lattice 148. The overpotential was decreased from 492 to 303 mV after incorporation of Co, and the improved activity was ascribed to the presence of Co(II/III) species that improved the binding of reactants and facilitated the formation of *OOH intermediate.…”

Recent Advances in Layered Tungsten Disulfide as Electrocatalyst for Water Splitting

“…And the overpotential at a current density of 10 mA cm À 2 was 121 mV and the Tafel slope was 67 mV dec À 1 (Figure 12g-h). In addition, Xu et al [77] prepared the Co-doped WS 2 and analyzed the OER performance. The doped Co existed in the form of Co 2 + and Co 3 + due to the electronic interaction between Co and S elements.…”

“…And the overpotential at a current density of 10 mA cm −2 was 121 mV and the Tafel slope was 67 mV dec −1 (Figure g–h). In addition, Xu et al . prepared the Co‐doped WS 2 and analyzed the OER performance.…”