Overconsumption of single-use plastics is creating a global waste catastrophe, with widespread environmental, economic, and health-related consequences. Inspired by the benefits of processive enzyme-catalyzed conversions of biomacromolecules and guided by spectroscopic interrogations of conformation and dynamics of polymer-surface interactions, we have developed the selective hydrogenolysis of high density polyethylene into a narrow distribution of diesel and lubricant-range alkanes catalyzed by an ordered, mesoporous shell/active site/core catalyst architecture. Solid-state nuclear magnetic resonance investigations of polymer chains adsorbed onto solid materials reveal that an appropriately ordered, porous support orients polymer chains into an all-anti conformation, while measurements of polymer dynamics reveal that long hydrocarbon macromolecules readily move within the pores, with a subsequent escape being inhibited by polymer-surface interactions. These interactions and dynamic behavior resemble the binding and translocation of macromolecules in the catalytic cleft of processive enzymes. Thus, transfer of these features to a mesoporous silica material incorporating catalytic platinum sites for carbon-carbon bond hydrogenolysis of polyethylene provides a reliable stream of alkane products through a processive process.

A catalytic architecture, comprising a mesoporous silica shell surrounding platinum nanoparticles (NPs) supported on a solid silica sphere (mSiO2/Pt-X/SiO2; X is the mean NP diameter), catalyzes hydrogenolysis of melt-phase polyethylene (PE) into a narrow C23-centered distribution of hydrocarbons in high yield using very low Pt loadings (∼10–5 g Pt/g PE). During catalysis, a polymer chain enters a pore and contacts a Pt NP where the C–C bond cleavage occurs and then the smaller fragment exits the pore. mSiO2/Pt/SiO2 resists sintering or leaching of Pt and provides high yields of liquids; however, many structural and chemical effects on catalysis are not yet resolved. Here, we report the effects of Pt NP size on activity and selectivity in PE hydrogenolysis. Time-dependent conversion and yields and a lumped kinetics model based on the competitive adsorption of long vs short chains reveal that the activity of catalytic material is highest with the smallest NPs, consistent with a structure-sensitive reaction. Remarkably, the three mSiO2/Pt-X/SiO2 catalysts give equivalent selectivity. We propose that mesoscale pores in the catalytic architecture template the C23-centered distribution, whereas the active Pt sites influence the carbon–carbon bond cleavage rate. This conclusion provides a framework for catalyst design by separating the C–C bond cleavage activity at catalytic sites from selectivity for chain lengths of the products influenced by the structure of the catalytic architecture. The increased activity, selectivity, efficiency, and lifetime obtained using this architecture highlight the benefits of localized and confined environments for isolated catalytic particles under condensed-phase reaction conditions.

Fundamentally altering the essential properties of a material itself is always of great interest but challenging as well. Herein, we demonstrate a simple tellurium doping method to intrinsically reshape the electronic properties of the sulfur and manipulate the kinetics of Li–S chemistry for improving the performance of Li–S batteries. DFT calculation indicates that Te doping can effectively facilitate the lithiation/delithiation reactions and lower the lithium ion diffusion energy barrier in Li2S. Additionally, electrochemical studies prove that the reaction kinetics of Li–S chemistry and cycling performance of Li–S batteries have been significantly improved with Te dopants. An exceptional specific capacity of ∼656 mA h g–1 and a high Coulombic efficiency of ∼99% have been achieved at 5 A g–1 even after 1000 cycles. More importantly, the capability to manipulate the intrinsic properties of materials and explore the synergistic effects between conventional strategies and element doping provides new avenues for Li–S batteries and beyond.