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Enhanced Fuel Decomposition in the Presence of Colloidal Functionalized Graphene Sheet-Supported Platinum Nanoparticles

Summary

Experiments and ReaxFF MD address Pt nanoparticles on functionalized graphene (Pt@FGS) in n-dodecane under supercritical conditions. Under 4.75 MPa and 753–803 K, a suspension of 50 ppmw Pt@FGS (reported as ~10 ppmw Pt) increases fuel conversion by up to ~24% and strongly increases H₂ yield (up to ~12.5× in the abstract’s comparison). ReaxFF trajectories of n-dodecane pyrolysis support a synergistic Pt–FGS mechanism favoring dehydrogenation relative to FGS-only or Pt-cluster baselines. Pt@FGS is reported colloidally stable; post-reaction Pt–FGS characterization shows no gross deterioration of the composite under the conditions studied.

Methods

  • Experiments: Supercritical n-dodecane pyrolysis at 4.75 MPa and 753, 773, or 803 K with 5.0 mL/min flow; loadings 50 ppmw Pt@FGS (quoted as ~10 ppmw Pt), FGS, Pt cluster, and neat fuel baselines; K-type thermocouples and degas at 0.05 MPa before pressurization (see article for reactor and GC analytics).
  • ReaxFF MD (ADF): ReaxFF for C/H/O/Pt in ADF (parallel ReaxFF-MD); energy minimization, equilibration at 100 K, then heat to 3000 K at 10 K/ps; production NVT at 1500-1900 K for 1.0 or 2.0 ns, time step 0.2 fs. NVT product snapshots at ~0.31 g/cm3 (see figure discussion).

MD application (n-dodecane pyrolysis). Amsterdam Density Functional (ADF) reactive molecular dynamics (ReaxFF for C/H/O/Pt); 3D PBC supercells of n-dodecane (with Pt/FGS chemistry as in the paper) near 0.31 g cm⁻³; 0.2 fs timestep; thermostat-controlled NVT production segments at 1500–1900 K for 1.0 or 2.0 ns after a 10 K ps⁻¹ ramp to 3000 K from a 100 K preequilibration (see pdf_path for the full sequence). Pressure: the 4.75 MPa and bar-scale reactor readings are for the flow-reactor (experiment); the NVT reactive trajectories as summarized are run at constant volume with no hydrostatic barostat in those 1–2 ns stages (see article if a separate NPT preequilibration exists). Barostat: N/A in the quoted NVT spans (constant-cell). Shear / shock, static electric field, umbrella / replica: N/A** in the ReaxFF ramp as summarized here.

Findings

  • Pt@FGS additives stabilize Pt in suspension and, under the reported supercritical conditions, increase fuel conversion compared with relevant baselines.
  • At 50 ppmw Pt@FGS, conversion increases by up to ~24%, with large increases in low-MW pyrolysis products and H₂ yield up to ~12.5× relative to the comparison cited in the abstract.
  • ReaxFF MD supports a mechanism in which Pt and FGS act together to promote dehydrogenation during n-C₁₂H₂₆ pyrolysis, more so than either component alone in the modeled scenario.
  • Post-reaction examination of platinum-decorated FGS suggests no significant degradation of the composite particle morphology or function under the reported conditions.

Together, the reactor data and atomistic trajectories support a picture in which nanoscale Pt and functionalized graphene cooperate at the fuel–additive interface, shifting pyrolysis branching toward dehydrogenation-favored product channels under the stated supercritical conditions. Limitations and outlook (as in article): see ## Limitations; reactor pressure (MPa) in experiment is not the same constraint as NVT reactive MD—compare across stages only with the PDF.

Limitations

Atomistic models necessarily simplify nanoparticle–solvent interfaces and long-time kinetics; quantitative alignment with the flow-reactor experiments requires careful comparison of temperature, pressure, and time scales between MD and experiment.

Relevance to group

van Duin co-authorship; combines jet-fuel–relevant pyrolysis chemistry with ReaxFF interpretation of metal–carbon synergy.

Citations and evidence anchors

  • DOI: 10.1021/acsaem.0c01010