Just recently, the "Advanced Materials" journal published significant research progress in the field of photocatalytic CO₂ reduction by Professor Zhou Xiaoyuan's team from Chongqing University. Based on the metal-coordination concept, they proposed an in-situ synthesis strategy using precursor thiourea molecules to anchor and separate single atoms before polymerization into CN-based supports, successfully achieving high-loading and large-scale preparation of single-atom catalysts (SACs).
Taking Cu SACs as an example, a single batch can produce 3.565 kg, with a metal single-atom loading of 16.03 mol%. This catalyst can also achieve high activity (274.88 μmol·g⁻¹·h⁻¹) and high selectivity (> 99%) conversion of CO₂ to HCOOH, leading the world. Additionally, this method is universal and can be extended to the synthesis of SACs with other elements, opening up new prospects for the industrial application of SACs. The CO₂ reduction reaction equipment used in the article is the Porphyrin PLR MFPR-I multifunctional photochemical reactor.
Inspired by knowledge of metal-coordination complexes, the team proposed a novel metal-coordination route. This route mainly involves the rapid complexation of ligands (such as thiourea) with metal ions in aqueous solution to form complexes, followed by in-situ thermal polymerization of the complexes to achieve high-load, large-scale preparation.
Highlight 1: Aberration-corrected electron microscopy + synchrotron radiation + DFT calculations demonstrate successful high-dose, high-load single-atom preparation
By using thiourea and various transition metal salts as precursors and preforming a thiourea reaction, the effective separation and anchoring of metal ions are achieved. Subsequently, only a simple one-step thermal treatment is required to generate high-load, large-scale single-atom catalysts.
Highlight 2: High loading density of single atoms can effectively improve the conversion efficiency of CO₂ to HCOOH and has universality
As shown in Figure 4, the CN substrate exhibits very low catalytic activity, but with the introduction of Cu single atoms, a large amount of HCOOH and a small amount of CH₄/CO are produced on Cu/CN, indicating that the introduction of Cu single atoms plays an important role in improving the catalyst's activity. Particularly, as the loading of single atoms increases, their photocatalytic performance also improves. The results show that catalytic activity depends on the loading of single atoms, and more active sites can be created by adjusting the loading, thereby enhancing the photocatalytic performance of the catalyst.
To further extend the universality of this metal-coordination strategy, the team also applied it to other transition metals, achieving industrial-scale synthesis of a series of transition metal SACs (M/CN, M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn). The advantage of this method lies in the rapid complexation of metal ions with thiourea, avoiding multiple washing and heating steps, which helps prevent mass loss and enables large-scale production of SACs. Most importantly, the key to this method is maximizing the bonding between metal and amide groups, achieving high-density metal loading.
This study explores a low-cost, large-scale preparation pathway for SACs, providing possibilities for potential industrial applications.
PLR MFPR-I multifunctional photochemical reactor has 4 major features:
1. Realize multi-field synergistic catalysis of photo-thermal pressure
The device's reaction system can reach a temperature of up to 180°C (temperature control accuracy ±0.5°C) and a pressure of up to 0.9 MPa, achieving a wide range of temperature and pressure adjustments, and realizing multi-field synergistic catalysis of photo-thermal pressure;
2. Fully automatic online sampling
The built-in sampling valve group can achieve joint use with chromatography. Fully automatic online sampling can be performed at different pressures from 50 kPa to 0.9 MPa at a high temperature of 180°C, improving experimental efficiency and reducing human error;
3. Strong compatibility
The multifunctional kettle lid combines diversified illumination methods of top and side illumination, compatible with photocatalytic, photoelectrocatalytic, and photo-thermal catalytic CO₂ reduction reactions;
4. High integration
The reaction system integrates heating, stirring, and automatic sampling modules into one, with a compact size to save space.
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With the help of the PLR MFPR-I multifunctional photochemical reactor, Professor Zhou Xiaoyuan's team has published many high-impact factor articles in the past two years, all of which used this equipment!
