Graphene-Supported Single Nickel Atom Catalyst for Highly Selective and Efficient Hydrogen Peroxide Production

Abstract

Hydrogen peroxide (H2O2) production by electrocatalytic two-electron oxygen reduction shows promise as a replacement for energy-intensive anthraquinone oxidation or H2/O2 direct synthesis. Here, we report on graphene-supported Ni single-atom (SA) electrocatalysts, which are synthesized by a simple surfactant-free reduction process with enhanced electrocatalytic activity and stability. Unlike conventional Ni nanoparticles or alloy catalysts, the well-dispersed Ni-SA sites lack adjacent Ni atoms. This structure promotes H2O2 production by a two-electron oxygen reduction pathway under an alkaline condition (pH = 13). This catalyst exhibited enhanced H2O2 selectivity (>94%) with a considerable mass activity (2.11 A mgNi –1 at 0.60 V vs reversible hydrogen electrode), owing to the presence of oxygen functional groups and isolated Ni sites. Density functional theory calculations provide insights into the role of this catalyst in optimizing the two-electron oxygen reduction reaction pathway with high H2O2 selectivity. This work suggests a new method for controlling reaction pathways in atomically dispersed non-noble catalysts.

Selective Electrocatalytic Reduction of Oxygen to Hydroxyl Radicals via 3‐Electron Pathway with FeCo Alloy Encapsulated Carbon Aerogel for Fast and Complete Removing Pollutants

“…[23] Both stronger and weaker binding to *OOH would bring additional overpotential, causing ab ottleneck for the reduction of *OOH to H 2 O 2 . [24] Notably,for Fe 0.5 Co 0.5 Cwith -COOH it was 0.13 eV downhill to form *OOH at U 0 O 2 =H 2 O 2 ,s uggesting that the lowest thermodynamic overpotential of 0.13 Vwas required to drive the reaction. However,c atalysts such as Au, [25] Pt, [25] Pd, [10a] CN [10c] respectively with higher thermodynamic overpotential of 0.39, 0.40, 0.16, 0.54 Vw ere not sufficiently active to motivate the 2-electron ORR.…”

Electrochemical Oxygen Reduction to Hydrogen Peroxide via a Two‐Electron Transfer Pathway on Carbon‐Based Single‐Atom Catalysts

“…Data from: PtHg 4 [ 16 ] ; Pt/HSC [ 62 ] ; Mn–NC, Fe–NC, Cu–NC, Co–NC, and Ni–NC [ 65 ] ; Co 1 ‐NG(O) and Co 1 ‐NG(R) [ 63 ] ; Co–POC–O [ 86 ] ; Fe‐CNT and Red. Fe‐CNT [ 20 ] ; Mo 1 /OSG‐H [ 80 ] ; Ni‐N 2 O 2 [ 70 ] ; Ni‐SA/G‐0 [ 78 ] ; Pt/CNT_IL_SiO 2 and Rh/CNT_IL_SiO 2 . [ 66 ] b) Computed U L values of 31 SACs in comparison with the PtHg 4 benchmark ( U L = 0.46 V).…”

“…The practice of replacing all nitrogen with oxygen as coordinating atoms has also been successfully realized by Bian and co‐workers [ 78 ] who achieved this conjecture by a simple and surfactant‐free reduction of Ni precursor on graphene oxidized (GO). EXAFS spectrum confirmed that the Ni atoms were dispersed in Ni‐SACs owing to the dominant Ni–O peak at 1.63 Å and there were no peaks observed at 2.18 and 2.61 Å belonging to the Ni–Ni and Ni–O–Ni contributions, respectively.…”

Electrocatalytic Oxygen Reduction to Hydrogen Peroxide: From Homogeneous to Heterogeneous Electrocatalysis

“…In the whole reaction process, the reaction of O selectivity of 94%, owing to the presence of oxygen functional groups and isolated Ni sites. [98]…”