Multidimensional regulation of interfacial microenvironment by alkali metal ions for selective photothermal CO₂ conversion

Photothermal CO₂ conversion holds significant potential for sustainable fuel synthesis. However, achieving selective control toward high-value multi-carbon products remains a fundamental challenge, constrained by the complex coupling of electronic, energetic, and kinetic factors at the catalyst interface. In this context, alkali metal ions (Li⁺, Na⁺, K⁺, Cs⁺) serve as dynamic “multidimensional interface modulators”. By promoting the accumulation and enrichment of interfacial electrons, they overcome the traditional trade-off between activity and selectivity in catalysis. We propose a unified “electron–energy–process” three-dimensional synergistic framework to elucidate their cross-scale regulatory mechanisms: (i) at the electronic level, modulating the electron density of active sites and the adsorption behavior of intermediates through electrostatic induction and charge rearrangement; (ii) at the energy level, constructing local electric fields to enhance the separation and migration efficiency of photogenerated carriers; (iii) at the process level, driving the dynamic reconstruction of photothermal interfaces to steer reaction pathways toward the evolution of high-value products. This framework systematically elucidates the role mechanisms of alkali metals across diverse systems, including carbon-based materials, metal interfaces, semiconductors, and insulators, integrating previously fragmented mechanistic insights into a unified design paradigm. We further identify key current challenges—such as dynamic interfacial evolution, alkali metal loss, and the integration of scalable reactors—and outline promising frontier strategies involving in situ characterization, machine learning-assisted catalyst design, and multi-field coupled systems. By offering a multidimensional perspective spanning from atomic-scale regulation to macroscopic process optimization, this review aims to accelerate the development of highly selective, stable, and efficient photothermal CO₂ conversion technologies, thereby contributing to the goal of achieving carbon neutrality.