CO2 Hydrogenation‐Induced Size‐Dependent Strong Metal‐Support Interactions in Platinum/Titanium Dioxide Catalysts

Why It Matters

The ability to control SMSI via particle size offers a practical route to boost CO₂ conversion efficiency in high‑temperature RWGS processes, accelerating carbon‑neutral fuel production. It also provides a design principle for other metal‑oxide catalysts where interfacial electronic structure governs activity.

Key Takeaways

• 7 nm Pt NPs show mild EMSI, higher CO2 conversion.
• 4 nm Pt NPs experience ultra‑EMSI, strong TiO2‑x encapsulation.
• Discontinuous TiO2‑x overlayer preserves Pt–O–Ti active sites.
• Mild EMSI delocalizes Pt d‑electrons, lowers RWGS activation energy.
• NP size tunes metal‑support interaction strength for catalyst design.

Pulse Analysis

The reverse water‑gas shift (RWGS) reaction is a cornerstone for converting captured CO₂ into syngas, a feedstock for sustainable fuels. While high temperatures favor thermodynamic conversion, catalyst durability and activity remain limiting factors. Strong metal‑support interactions (SMSI) have emerged as a key lever to modify electronic properties of active sites, yet controlling SMSI intensity without sacrificing surface accessibility has proven challenging for traditional Pt/TiO₂ systems.

In the recent study, researchers leveraged in‑situ CO₂ hydrogenation to induce size‑dependent SMSI on rutile TiO₂. Larger Pt nanoparticles (~7 nm) formed a discontinuous TiO₂₋ₓ overlayer, resulting in mild electronic metal‑support interaction (EMSI) that retained exposed Pt–O–Ti interfacial sites. Conversely, smaller particles (~4 nm) were fully encapsulated, experiencing ultra‑EMSI that blocked active sites. Spectroscopic analyses and density‑functional theory revealed that mild EMSI promotes d‑electron delocalization on Pt, weakening adsorbate binding and lowering the activation barrier for CO₂ reduction, which translated into a 1.7‑fold boost in conversion at 800 °C.

These insights position nanoparticle size engineering as a scalable strategy to fine‑tune SMSI across a range of metal‑oxide catalysts. By balancing encapsulation and electronic coupling, manufacturers can design catalysts that deliver higher turnover rates while maintaining resistance to sintering under harsh reaction conditions. The approach also opens pathways for optimizing other reactions—such as CO oxidation or methane reforming—where interfacial chemistry dictates performance, reinforcing the broader relevance of size‑controlled SMSI in the transition to low‑carbon industrial processes.