Dr Roberto Volpe
PhD
Research Overview
Pyrolysis, Renewable carbons, Synchrotron-based X-ray and electron imaging, Water remediation, polymer-based composites, Catalysis
Interests
My research addresses the coupled chemistry and transport phenomena that govern the thermochemical conversion of biomass and waste, and in particular how char microstructure evolves during pyrolysis. My group develops lab- and synchrotron-based in situ and operando methods to resolve these processes as they happen. Synchrotron phase-contrast radiography and X-ray micro-computed tomography at the UK national synchrotron, Diamond Light Source, follow single particles and packed beds through devolatilisation at sub-micron to nanometric voxel resolution. In situ heating transmission electron microscopy at ePSIC extends this to the atomic and sub-nanoscale, resolving carbon restructuring and the evolution of metal phases within the char.
Our approach produced the first in situ phase-contrast X-ray imaging study of biomass pyrolysis, which linked feedstock composition and alkaline pretreatment to particle shrinkage and pore migration away from the particle surface (Scientific Reports, 2021). Later operando tomography of single particles revealed transient swelling regimes, consistent with softening of native lignin-associated biopolymers. Pre-washing particles suppressed swelling and changed the outcome: volumetric shrinkage rose from about 30% to about 70%, and central porosity developed about 3.5 times faster. A radial pore-distribution descriptor we introduced showed a linear temperature dependence, pointing to heat- and mass-transfer limitations within the particle (Biochar, 2024).
We use this mechanistic insight to design hierarchically porous carbons with controlled pore architecture, surface functionality and active-site chemistry. Examples include:
- biochar scaffolds whose pore-surface hydrophilicity is tuned through pretreatment
- templated carbons derived from sporopollenin exine capsules
- metal-decorated micro-chars bearing Fe, Fe3C or Fe–N–C sites anchored on or encapsulated in graphitic carbon
These materials target heterogeneous catalysis, including the reverse water–gas shift reaction for CO₂ conversion and the oxygen reduction reaction. They also target adsorptive and filtration-based water remediation, such as removing drug-resistant bacteria and pharmaceutical residues (Scientific Reports, 2025), and polymer-based composites. In parallel, we study iron as a catalyst precursor in plastic-waste pyrolysis, where in situ-formed iron species show an auto-catalytic effect on depolymerisation and product upgrading.