# CQD-Modified SrTiO3 for Enhanced Photocatalytic CO2 Reduction to Methane

## TL;DR

Researchers improved SrTiO3 with carbon quantum dots to boost its ability to convert CO2 into methane under visible light, making it more efficient and stable.

## Contribution

A novel SrTiO3/carbon quantum dot heterojunction was developed for enhanced CO2-to-CH4 photocatalysis without high-temperature treatment or noble metals.

## Key findings

- CQD modification extended SrTiO3's visible-light absorption to 420 nm and improved charge separation efficiency.
- The SrTiO3/CQDs composite achieved a CH4 evolution rate of 1.16 μmol·g−1·h−1, 16.3 times higher than pure SrTiO3.
- The catalyst remained stable over four cycles, showing structural robustness and reusability.

## Abstract

SrTiO3 has attracted considerable attention owing to its favorable electronic structure and chemical stability among various semiconductor photocatalysts. However, its practical application is hindered by a wide bandgap and rapid recombination of photogenerated charge carriers. Herein, we report the fabrication of a SrTiO3/carbon quantum dot (CQD) heterojunction via a two-step hydrothermal method for efficient CO2-to-CH4 photocatalysis, a strategy that circumvents the need for high-temperature treatment and noble metals. TEM images revealed well-defined lattice fringes and intimate interfacial contact between SrTiO3 and CQDs, suggesting efficient charge transfer pathways. Optical measurements confirmed that CQD modification extends the visible-light absorption range of SrTiO3 to 420 nm while significantly enhancing charge separation efficiency. The SrTiO3/CQDs composite with 10 wt% CQD loading exhibited optimal activity, achieving a CH4 evolution rate of 1.16 μmol·g−1·h−1—16.3 times higher than that of pristine SrTiO3. Mechanistic investigations demonstrate that CQDs serve as efficient electron reservoirs, facilitating interfacial charge transfer and suppressing the recombination of photogenerated charge carriers. The catalyst maintained stable performance over four consecutive cycles, confirming its structural robustness and reusability. This work demonstrates that CQD modification effectively enhances the visible-light response and charge separation efficiency of SrTiO3, offering a viable strategy for designing high-performance photocatalysts toward solar fuel production.