2026-09-21

CEJ: Built-In Interfacial Fields Drive Selective CO₂-to-CO Photoreduction

Research highlight. A 2026 Chemical Engineering Journal paper reports a quasi-two-dimensional g-C₃N₄/Cs₂CuBr₄ (CCB) heterostructure for selective photocatalytic CO₂-to-CO conversion. The study focuses on how interfacial built-in electric fields influence charge migration and CO₂ activation.

Why Conventional Type-I Alignment Can Be Limiting

In a conventional Type-I heterojunction, photogenerated electrons and holes may accumulate in one semiconductor. Although this can be useful for certain optical processes, it can also limit the retention of strongly reducing electrons needed for CO₂ conversion. Interface design is therefore central to balancing charge separation with redox capability.

Interface Engineering with CCB Nanoclusters

The authors anchored Cs₂CuBr₄ nanoclusters in situ onto two-dimensional g-C₃N₄. The resulting quasi-two-dimensional contact was designed to create a stable interfacial region rather than a simple physical mixture.

Synthesis and structural characterization of the CCB heterostructure — Figure 1. Synthesis, morphology and structural characterization of the g-C3N4/Cs2CuBr4 heterostructure.

Built-In Electric Field and Z-Scheme-Like Charge Migration

The source describes a non-classical Type-I alignment in which the built-in electric field drives Z-scheme-like charge transfer under illumination. This pathway enriches electrons on g-C₃N₄, helping retain reduction capability while promoting CO₂ adsorption and activation.

Evidence Chain for Structure, Charge Dynamics and CO₂ Activation

The study combines XRD, BET, XPS, in situ XPS, Kelvin probe force microscopy, ESR, femtosecond transient absorption, photocurrent and impedance measurements with CO₂ adsorption, temperature-programmed desorption, DRIFTS and DFT analysis. Together, these methods connect structural interface design with observed catalytic behavior.

Diffraction adsorption and electronic structure characterization — Figure 2. Diffraction, adsorption and electronic-structure characterization.

Reaction Evaluation Context

The source article reports use of a predecessor of the μGAS1001 micro-gas reaction evaluation system. In research on gaseous products, the light source, reactor, gas handling, sampling sequence, calibration and data processing should be treated as one experimental chain. See photothermal and photocatalytic reaction systems for related system configurations.

Figure 3. Photocatalytic CO2-to-CO performance and reaction evaluation.

Charge transfer pathway and interface model — Figure 4. Charge-transfer pathway and interface model.

Figure 5. Spectroscopic and photoresponse evidence.

Figure 6. Temperature-programmed and in situ reaction analysis.

Figure 7. Additional catalytic characterization and product selectivity.

Reference

L. Dong, Q. Zeng, X. Zhong, et al. Interface-engineered built-in electric fields in g-C₃N₄/Cs₂CuBr₄ non-classical Type-I heterostructures for selective CO₂-to-CO conversion. Chemical Engineering Journal 2026, 531, 173817. DOI: 10.1016/j.cej.2026.173817.

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