Manipulating the oxygen reduction reaction pathway on Pt-coordinated motifs

Abstract

Electrochemical oxygen reduction could proceed via either 4e−-pathway toward maximum chemical-to-electric energy conversion or 2e−-pathway toward onsite H2O2 production. Bulk Pt catalysts are known as the best monometallic materials catalyzing O2-to-H2O conversion, however, controversies on the reduction product selectivity are noted for atomic dispersed Pt catalysts. Here, we prepare a series of carbon supported Pt single atom catalyst with varied neighboring dopants and Pt site densities to investigate the local coordination environment effect on branching oxygen reduction pathway. Manipulation of 2e− or 4e− reduction pathways is demonstrated through modification of the Pt coordination environment from Pt-C to Pt-N-C and Pt-S-C, giving rise to a controlled H2O2 selectivity from 23.3% to 81.4% and a turnover frequency ratio of H2O2/H2O from 0.30 to 2.67 at 0.4 V versus reversible hydrogen electrode. Energetic analysis suggests both 2e− and 4e− pathways share a common intermediate of *OOH, Pt-C motif favors its dissociative reduction while Pt-S and Pt-N motifs prefer its direct protonation into H2O2. By taking the Pt-N-C catalyst as a stereotype, we further demonstrate that the maximum H2O2 selectivity can be manipulated from 70 to 20% with increasing Pt site density, providing hints for regulating the stepwise oxygen reduction in different application scenarios.

Tailoring the selectivity and activity of oxygen reduction by regulating the coordination environments of carbon-supported atomically dispersed metal sites

“…This originality of coordinated configuration received recognition from Jiang and co-workers. 70 Jiang et al prepared a series of Pt C-ADMSs with directly varied coordination atoms (C, N, and S) to regulate the local coordination environment effect to manipulate the ORR pathways. Fourier-transformed extended X-ray absorption fine structure (FT-EXAFS) spectra were employed to confirm the structural state of Pt in the first shell and no Pt–Pt or Pt–O interaction existed.…”

“…Manipulating the ORR pathway to achieve distinct selectivity was realized on Pt-coordinated motifs. 70 With the varied first coordinated dopants such as N, S and C, the as-synthesized Pt–N–C, Pt–S–C and Pt–C configurations were prepared and characterized by EXAFS and XANES. Compared to the Pt–C moiety, the exotic atoms S and N directly coordinated with Pt centers had the distinct 2e − ORR selectivity.…”

Recent Advances in Anode Electrocatalysts for Direct Formic Acid Fuel Cell‐II‐Platinum‐Based Catalysts

“…The oxygen reduction at the cathode requires Ptbased catalysts. [36] Conversely, anode electrocatalysts are required because the FAO is intrinsically slow and oxidation to carbon dioxide requires a large overpotential. [27,37] Noble metal-, Pd-, and Pt-based catalysts have promising performance to accelerate the slow anodic FAO.…”

“…Electrocatalysts are required at the cathode and anode of a PEMFC. The oxygen reduction at the cathode requires Pt‐based catalysts [36] . Conversely, anode electrocatalysts are required because the FAO is intrinsically slow and oxidation to carbon dioxide requires a large overpotential [27,37] .…”

Rational design of 2D ferroelectric heterogeneous catalysts for controllable hydrogen evolution reaction

“…2,[5][6][7] During this process, efficient catalysts with high stability and selectivity play a crucial role in improved electrocatalytic performance. Thus, seeking suitable electrocatalysts has been widely conducted in different chemical reactions, for example, the hydrogen evolution reaction (HER), [8][9][10][11] oxygen evolution reaction (OER), [12][13][14] oxygen reduction reaction (ORR), [14][15][16][17] carbon dioxide reduction reaction (CO 2 RR), 6,[18][19][20] and and nitrogen reduction reaction (NRR). [21][22][23][24] According to the Sabatier principle, the ideal catalytic efficiency can be attained when the adsorbate-catalyst interaction strength is optimal for easy electron transfer and ready breakage to release the product.…”