The research group led by Chen Rong at Wuhan Textile University recently reported a bimetallic Pt-Rh/TiO₂ photocatalyst that efficiently converts toxic carbon monoxide (CO) and H₂O into ethylene (C₂H₄) under room temperature (25 ℃) and ambient pressure conditions. By precisely controlling the atomic ratio of Pt to Rh (optimal ratio 2:8), the study achieved a high C₂H₄ yield of up to 362.94 µmol·g⁻¹ with a selectivity of 45%, maintaining stable performance under continuous illumination for 26 hours. Combined with in situ characterization and DFT calculations, the results revealed that Rh sites in the Pt-Rh alloy act as the main active centers for CO reduction, promoting electron accumulation and asymmetric C-C coupling, significantly lowering the reaction barrier and providing a new strategy for CO valorization under mild conditions.
No.1 Solar-Driven Catalytic System for CO-to-C₂H₄ Conversion
Achieves direct and highly selective synthesis of ethylene from CO and H₂O driven by solar energy at room temperature and atmospheric pressure. This system overcomes the limitations of traditional thermal catalysis (requiring 200–450 ℃) and electrocatalysis (low selectivity), maintaining a reaction temperature at 25 ℃. The C₂H₄ yield reaches 362.94 µmol·g⁻¹ with 45% selectivity, providing a novel pathway for low-temperature CO conversion.
No.2 Revealing Synergistic Electronic Effects and Key Intermediates of Pt-Rh Bimetallics
In situ XPS and UPS confirm directional electron transfer from Pt to Rh sites under illumination, causing a negative shift of 0.11 eV in Rh 3d binding energy and a positive shift of 0.09 eV in Pt 4f, significantly enhancing the electron density at Rh sites and their activation ability toward CO. In situ DRIFTS captured key C-C coupling intermediate COCO (1712 cm⁻¹) and mixed adsorption configuration CO bridge (1892 cm⁻¹), clarifying the reaction pathway.
No.3 Outstanding Catalytic Stability and Anti-Coking Ability
The catalyst shows no performance decay after 26 hours of continuous illumination. Post-reaction XRD, TEM, and XPS characterizations indicate unchanged crystal structure, morphology, and metal chemical states; ICP tests confirm no metal leaching, demonstrating excellent stability and anti-coking capability, with promising practical application potential.
Figure 1. Catalyst synthesis and characterization. (a) Schematic of Pt-Rh/TiO₂ synthesis process. (b) PXRD patterns of Pt-Rh/TiO₂ and Pt-Rh alloy. (c) Scanning Transmission Electron Microscopy (STEM) images, (d) particle size distribution, (e) High-Resolution Transmission Electron Microscopy (HRTEM) images, (f) double Cs-corrected TEM images, (g) atomic-resolution EDX mapping, and (h) line EDX of Pt-Rh/TiO₂.
Figure 2. Photocatalytic performance of Pt-Rh/TiO₂. Reaction conditions: 10 mg catalyst dispersed in solution, 300 W xenon lamp illumination, reactor purged with Ar (99.99%) and CO (99.99%) at a volume ratio of 4:1, reaction temperature maintained at 25°C. (a) Photocatalytic CO reduction (COR) activity and (b) selectivity relative to Pt-Rh/TiO₂. (c) Stability of photocatalytic COR under optimized conditions. (d) GC-MS spectra of C₂H₄ production under ¹³CO atmosphere. (e) Photocatalytic CO₂ reduction (CO2R) activity under same conditions but with CO replaced by CO₂. (f) and (g) Comparison of C₂H₄ production within 3 h under CO and CO₂ atmospheres, respectively.
Figure 3. Photoelectrochemical properties of Pt-Rh/TiO₂. (a) UV-Vis diffuse reflectance spectra; (b) bandgap derived from DRS; (c) X-ray photoelectron valence band spectra; (d) semiconductor band structure; (e) transient photocurrent response; (f) electrochemical impedance spectroscopy; (g) linear sweep voltammetry; (h) Mott-Schottky plots of TiO₂, Pt/TiO₂, Rh/TiO₂, and Pt-Rh/TiO₂ photocatalysts.
Figure 4. Studies on photoelectrochemical properties and charge transfer. Using 300 nm light as pump source, 2D false-color transient absorption (TA) spectra at different time scales for (a) TiO₂, (b) Pt/TiO₂, (c) Rh/TiO₂, and (d) Pt-Rh/TiO₂. Multi-exponential fs-TA kinetic fitting for (e) TiO₂, (f) Pt/TiO₂, (g) Rh/TiO₂, (h) Pt-Rh/TiO₂. In situ light-illuminated XPS spectra of (i) Pt 4f and (j) Rh 3d in Pt-Rh/TiO₂. (k) UPS spectra of TiO₂, Pt/TiO₂, Rh/TiO₂, and Pt-Rh/TiO₂.
Figure 5. Photocatalytic reaction mechanism study. (a) Pt/TiO₂, (b) Rh/TiO₂, and (c) Pt-Rh/TiO₂ in situ time-resolved diffuse reflectance FTIR spectra. (d) Adsorption energies of CO_top and CO_bridge configurations on Rh/TiO₂ and Pt-Rh/TiO₂. Density of states (DOS) for CO_top and CO_bridge on (e) Rh/TiO₂ and (f) Pt-Rh/TiO₂. (g) Charge density difference maps of *CO_top*CO_top and *CO_bridge formed on Pt-Rh/TiO₂. (h) Calculated potential energy diagram for CO-to-C₂H₄ conversion on Pt-Rh/TiO₂. (i) Proposed photocatalytic CO reduction mechanism on Pt-Rh/TiO₂.
In the room-temperature and atmospheric pressure gas-solid catalytic reactions described above, achieving high-precision control over the reaction process and accurate quantification of gaseous products is a key step to advance in-depth mechanistic studies and catalyst optimization. To meet these needs, Porphile has launched the High-Precision Quantitative Evaluation Scheme for Trace Gas Reactions, dedicated to building a precise, reliable, and efficient experimental platform for demanding catalytic research. The scheme centers around the μGAS1000 Trace Gas Reaction Evaluation System, combined with various xenon lamp light sources (e.g., PLS-CS300, PLS-SXE300E, PLS-SME400E H1) and multiple detection modules, fully leveraging features such as intelligent upper computer control, strong stability, high accuracy, and broad compatibility, comprehensively supporting the entire research workflow from condition exploration to mechanistic analysis.
Key Features
No.1 Intelligent Control and Easy Operation
The xenon light sources and the μGAS1000 system come equipped with professional upper computer software. Xenon lamps (e.g., PLS-SXE300E, PLS-SME400E H1) support remote computer monitoring and adjustment of current and related parameters, significantly improving experimental efficiency. The μGAS1000 integrates automatic sampling and gas circulation modules, enabling long-term unattended operation. The upper computer software allows high-precision control of key parameters like pressure and temperature, automatically records experimental data, and intelligently exports reports, greatly aiding process review and result analysis.
No.2 Stable and Reliable with High Data Accuracy
To ensure experimental accuracy and reliability, the power supply fluctuation of xenon lamps (e.g., PLS-CS300) is controlled within ±2%, guaranteeing stable light intensity output. The μGAS1000 system features a new structural design with high gas tightness and a dynamic oxygen leak rate below 0.1 μmol/h. Its standard curve shows a linear regression coefficient > 0.999, with relative standard deviation (RSD) < 3% for four consecutive injections at the same concentration, reaching scientific-grade accuracy. This stability and reliability provide a solid foundation for precise experimental execution and data integrity.
No.3 Flexible Modules Compatible with Various Reactions
The high-precision quantitative evaluation scheme offers high modularity and expandability, allowing flexible replacement of illumination modules, reactors of various specifications, and different detection modules. This multi-module interchangeability enables comprehensive support for photocatalysis, electrocatalysis, photo-thermocatalysis under mild vacuum or atmospheric pressure, and other reaction systems, achieving high-precision evaluation and mechanistic study of gas-solid and gas-liquid multiphase catalytic processes.
In Conclusion
High-value conversion of CO is an important direction for carbon resource utilization. This study realized efficient photocatalytic conversion of CO to C₂H₄ at room temperature through Pt-Rh bimetallic synergy and interfacial electronic structure modulation, overcoming the harsh conditions and low selectivity limitations of traditional thermal and electrocatalysis. The high-precision quantitative evaluation scheme, with intelligent upper computer control, strong stability, and high accuracy, along with versatile compatibility, provides a reliable experimental foundation for such room-temperature and atmospheric pressure reaction studies, accelerating the transition from fundamental research to practical application.
Reference
Chengxin Zhu, Wei Zhang, et al. Bimetallic Pt-Rh/TiO₂ boosting the room-temperature solar-driven CO selective conversion to ethylene. Applied Catalysis B: Environment and Energy, 380(2026) 125787.
