Unraveling the Impact of Graphene Addition to Thermoelectric SrTiO₃ and La-Doped SrTiO₃ Materials: A Density Functional Theory Study

Abstract

We present a detailed theoretical investigation of the interaction of graphene with the SrO-terminated (001) surface of pristine and La-doped SrTiO 3 . The adsorption of graphene is thermodynamically favorable with interfacial adsorption energies of −0.08 and −0.32 J/m 2 to pristine SrTiO 3 and La-doped SrTiO 3 surfaces, respectively. We find that graphene introduces C 2p states at the Fermi level, rendering the composite semimetallic, and thus the electrical properties are predicted to be highly sensitive to the amount and quality of the graphene. An investigation of the lattice dynamics predicts that graphene adsorption may lead to a 60−90% reduction in the thermal conductivity due to a reduction in the phonon group velocities, accounting for the reduced thermal conductivity of the composite materials observed experimentally. This effect is enhanced by La doping. We also find evidence that both La dopant ions and adsorbed graphene introduce lowfrequency modes that may scatter heat-carrying acoustic phonons, and that, if present, these effects likely arise from stronger phonon−phonon interactions.

In Tandem Control of La-Doping and CuO-Heterojunction on SrTiO3 Perovskite by Double-Nozzle Flame Spray Pyrolysis: Selective H2 vs. CH4 Photocatalytic Production from H2O/CH3OH

“…Domen [ 33 , 34 ] and Kudo [ 35 , 36 ] have demonstrated that SrTiO 3 co-doped with La and Rh exhibits high solar-to-hydrogen energy conversion efficiency for water splitting to H 2 . Moreover, selected cations, e.g., La 3+ , Ce 3+ , or Nitrogen [ 8 , 37 ] allow control of structural/photo/electronic properties of doped-SrTiO 3 , enhancing the photocatalytic efficiency [ 38 , 39 ]. Thus, SrTiO 3 offers a versatile template, that can be optimized towards specific technologies either via doping or heterojunction engineering.…”

Theoretical and Experimental Studies of Molecular Interactions between Engineered Graphene and Phosphate Ions for Graphene-Based Phosphate Sensing

“…Electrical conductivity σ was computed using Boltzmann transport equation with constant relaxation time as implemented in Boltztrap2 and pymatgyn, , using the formula σ = e 2 V ∑ k ( − ∂ f 0 false( ϵ k false) ∂ ε k ) v k v k τ k where f 0 ( ε k ) = 1 / ( exp ( ( ε k − ε F ) / k B T ) + 1 ) is the Fermi–Dirac distribution function, ∑ k means summation over k -points along the specified path in the Brillouin zone, e is the electron charge, V is the volume, v k is the group velocity, τ k is the relaxation time, ε F is the Fermi energy, k B is the Boltzmann constant, and T is the temperature. The temperature of 300 K was used, while τ k was set as constant at 1 × 10 –14 s. Constant relaxation time was used, because it has been shown to give reasonable agreement with experiment for room temperature studies. − The volume was taken as the surface area of graphene multiplied by the thickness of the single layer graphene, where the thickness i...…”

A Review of Key Properties of Thermoelectric Composites of Polymers and Inorganic Materials

“…For conventional/polymer composites, the nature of seems dependent upon the nature of the composite’s constituents, with higher polymer loadings linked to lower , due to more significant alterations to the band structure, or the interruption of conductive channels compared to the pristine conventional material [ 167 ]. Conversely, of conventional materials may be improved upon with small additions of polymer, due to the retainment of the band structure of the conventional material and/or overlap/alteration of the materials bandgap and Fermi region, as demonstrated in a recent theoretical study involving compositing a semi-conductive inorganic material with Graphene [ 178 , 179 ].…”