Sb2S3-templated synthesis of sulfur-doped Sb-N-C with hierarchical architecture and high metal loading for H2O2 electrosynthesis

Abstract

Selective two-electron (2e−) oxygen reduction reaction (ORR) offers great opportunities for hydrogen peroxide (H2O2) electrosynthesis and its widespread employment depends on identifying cost-effective catalysts with high activity and selectivity. Main-group metal and nitrogen coordinated carbons (M-N-Cs) are promising but remain largely underexplored due to the low metal-atom density and the lack of understanding in the structure-property correlation. Here, we report using a nanoarchitectured Sb2S3 template to synthesize high-density (10.32 wt%) antimony (Sb) single atoms on nitrogen- and sulfur-codoped carbon nanofibers (Sb-NSCF), which exhibits both high selectivity (97.2%) and mass activity (114.9 A g−1 at 0.65 V) toward the 2e− ORR in alkaline electrolyte. Further, when evaluated with a practical flow cell, Sb-NSCF shows a high production rate of 7.46 mol gcatalyst−1 h−1 with negligible loss in activity and selectivity in a 75-h continuous electrolysis. Density functional theory calculations demonstrate that the coordination configuration and the S dopants synergistically contribute to the enhanced 2e− ORR activity and selectivity of the Sb-N4 moieties.

An abnormal size effect enables ampere-level O2electroreduction to hydrogen peroxide in neutral electrolytes

“…As a consequence, the state-of-the-art oxygen electroreduction catalysts only allow moderate current densities of 0.05–0.3 A cm −2 with trade-off faradaic efficiencies (95–5%) in neutral electrolytes. 5,11,14–16…”

“…The principle of size effect has been extensively used to express the activity enhancement of catalysts as a result of size decreasing, 4,17,22–24 ranging from microscale-, nanoscale-, to cluster/single-atom catalysts. 5,9,16 Nevertheless, these small-sized catalysts only allowed smaller current densities in neutral electrolytes thus far (50–300 mA cm −2 ). 16,25 Inspired by this principle, in the present work, our original attempt was to synthesize and compare the activities of zinc oxide (ZnO) nanoplate catalysts with different thicknesses (87.7, 26.3 and 1.70 nm).…”

“…As a consequence, the state-of-the-art oxygen electroreduction catalysts only allow moderate current densities of 0.05-0.3 A cm À2 with trade-off faradaic efficiencies (95-5%) in neutral electrolytes. 5,11,[14][15][16] The principle of size effect was noticed more than a century ago, 17,18 but has recently rekindled enormous interest accompanying the discovery of nanomaterials, 19 graphene 20 and single-atom/clusters. 21 In geometry, small-size nanoparticles usually expose more low-coordination sites and high surface areas, and thus they can increase considerably the chemical bond breaking in catalysis.…”

“…5,9,16 Nevertheless, these small-sized catalysts only allowed smaller current densities in neutral electrolytes thus far (50–300 mA cm −2 ). 16,25 Inspired by this principle, in the present work, our original attempt was to synthesize and compare the activities of zinc oxide (ZnO) nanoplate catalysts with different thicknesses (87.7, 26.3 and 1.70 nm). In great contrast to traditional size effects, large-size ZnO nanoplates can break the intrinsic activity-selectivity trade-off relationship in a flow-type electrolytic cell, and has shown superior ORR activities characteristic of ∼100% selectivity to H 2 O 2 up to ampere-level current densities.…”

Carbon Black‐Supported Single‐Atom CoNC as an Efficient Oxygen Reduction Electrocatalyst for H2O2 Production in Acidic Media and Microbial Fuel Cell in Neutral Media

“…[9] The regulation of binding energy of *OOH on MNC catalysts can be achieved by changing the type or tailoring the coordination environment of central metal atom, leading to the regulation of ORR selectivity. [1][2][3]5,6,8,10,11] Although great success has been achieved in this field, it is still suppressed by the active…”