In humanity’s pursuit of sustainable energy conversion, catalysis has always been the core engine. Traditional chemical reactions typically rely on two extreme pathways: thermal catalysis provides energy to overcome thermodynamic barriers through external heating, activating molecular adsorption, but is often limited by reverse reaction equilibrium at high temperatures or catalyst sintering risks; photocatalysis uses photon-induced quantum effects to drive reactions under mild conditions, yet often suffers from fast charge recombination and low efficiency in converting low-density light energy. As research has deepened, scientists have discovered that the “dance” of light and heat can create unique chemical phenomena. This multi-field coupling strategy is reshaping our understanding of molecular bond cleavage and reconstruction.
From a fundamental physical perspective, the advantages of photothermal catalysis lie primarily in the utilization of energy ladders and kinetic compensation. Photon energy mainly induces the generation of photogenerated carriers in semiconductors or plasmon resonance on metal surfaces, while thermal energy assists diffusion, accelerates product desorption, and alters reaction pathways. This combination not only converts low-density solar energy into high-density chemical energy, but also enables reactions that normally require very high temperatures to proceed efficiently at lower macroscopic temperatures. For example, in exothermic reactions such as ammonia synthesis, thermodynamic equilibrium limits yield at high temperatures, whereas photothermal synergy can activate reactive sites through light excitation, overcoming this “zero-sum” limitation and achieving high conversion efficiency.
In practical laboratory research, constructing a highly controllable photothermal coupling environment is a key focus. Because natural sunlight is heavily influenced by weather, researchers prefer to simulate complex light and temperature fields indoors using precision equipment. For example, in gas–solid photothermal synergistic experiments, to decouple the respective contributions of photochemical and thermal effects, devices such as the PLR PTCS-31 Solar Photothermal Catalysis Simulation Experimental System are often used. This system employs a high-power LED array as the sole energy input and combines it with a high-absorption, low-radiation collection structure, enabling a purely photothermal environment with temperatures up to 500 °C in the reaction zone using light alone. In this way, researchers can precisely adjust the intensity of different wavelength bands to obtain bulk-phase temperature data of the catalyst under realistic illumination, providing a quantitative basis for kinetic mechanism analysis.
Beyond mechanistic exploration, time efficiency and energy utilization in experimental design are critical considerations for engineering applications. Traditional fixed-bed reactors, due to slow thermal equilibration, often require hours or even overnight to screen a single sample. Modern integrated platforms, such as rapid-heating multi-field fixed-bed reactors, incorporate embedded Joule heating and vacuum insulation, achieving programmatic heating in minutes. This design shortens the time to establish thermal equilibrium to less than 15 minutes, greatly enhancing high-throughput catalyst evaluation efficiency. Ingeniously, these systems adopt an annular illumination design, positioning photons close to the catalyst layer via quartz tube reactors, improving light utilization efficiency by approximately 60% compared to conventional top-illumination setups. This extreme utilization of costly photons and thermal energy provides the technical assurance for transitioning photothermal catalysis from laboratory-scale samples to scaled-up reactor beds.
Despite its advantages, industrial application of photothermal catalysis still faces practical challenges such as uneven physical field distribution and complex phase mass transfer. In large-area flat reactors or continuous-flow tubular reactors, light penetration depth limits make it challenging to ensure that large quantities of catalysts reside at optimal photothermal coupling points, requiring precise flow-field simulation and optical shaping. However, these challenges have driven the continuous evolution of research equipment. By integrating digitally feedback-controlled light sources and fully glass inert analysis systems, scientists can eliminate external environmental interference and directly probe the essence of charge transfer at the reaction interface. In this long marathon of pursuing “liquid sunlight,” photothermal synergistic technology not only provides a more efficient energy conversion scheme, but also reveals the limitless potential of controlling molecular behavior under non-equilibrium conditions.
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