“In the grand context of global carbon-neutral strategies, converting industrial CO₂ emissions into high-value fuels or chemicals has emerged as one of the most formidable challenges in contemporary chemistry and energy science. Artificial photosynthesis (AP) stands at the core of this vision, evolving from fundamental materials development toward complex system integration. Among the various technological pathways, photoelectrocatalysis (PEC) has demonstrated superior charge carrier separation efficiency and energy conversion limits compared with standalone photocatalysis, thanks to its dual advantage of direct light-driven activation and precise electrochemical control. For researchers with a foundational background, the key to understanding this process lies in elucidating the evolution of photogenerated charges at the semiconductor interface, electrolyte interface, and three-phase boundaries. The essence of PEC CO₂ reduction involves a multi-electron, multi-proton complex reduction process. Under illumination, a semiconductor photoanode absorbs photons to generate electron–hole pairs; holes drive the oxygen evolution reaction (OER) at the anode surface, while the light-excited electrons are “guided” by an external bias to migrate through the circuit to the cathode catalyst. This introduction of an external electric field fundamentally alters the recombination kinetics of photogenerated carriers, allowing electrons to reach active sites at higher energy states and effectively overcoming the intrinsic chemical stability of linear CO₂ molecules. However, this “light–electric–chemical” coupled system imposes stringent requirements on experimental uniformity and stability. In laboratory evaluation, factors such as the energy distribution of incident light, overlap precision between the light spot and electrodes, and bias fluctuations during the reaction can all exponentially affect the measured Faradaic efficiency. To acquire scientifically reproducible data under such complex, coupled energy fields, researchers require a highly standardized testing platform. The **PEC2000 Photoelectrochemical Testing System** is an integrated terminal specifically designed to meet these precise evaluation needs. In CO₂ reduction experiments, the system employs intelligent multi-position adjustment and laser-aligned optical paths to eliminate incidental errors from manual manipulation affecting light spot coverage and incident angles. This precise physical control ensures that during I–V curve measurements, I–t chronoamperometry, and electrochemical impedance spectroscopy (EIS), the photon flux incident on the material surface remains constant and quantifiable. In long-term stability tests, the system’s built-in optical feedback module compensates in real time for natural light source decay, allowing researchers to discern whether shifts in product selectivity originate from catalyst surface deactivation or perturbations in the external physical field. This provides a solid physical basis for constructing a reliable CO₂ reduction evaluation paradigm.
Beyond physical field management, the choice of reaction phase constitutes another technical bottleneck limiting conversion efficiency. Current research seeks a balance between liquid-phase suspension systems and gas–solid reaction modes. Because CO₂ solubility in aqueous solution under ambient conditions is only about 33 mM, liquid-phase reactions frequently encounter severe mass transport limitations. In contrast, gas diffusion electrodes (GDEs) or continuous-flow reactors leverage the high diffusion coefficients of gaseous substrates, significantly increasing substrate concentration near the interface and promoting formation of C₂ or higher-carbon products. However, as mass transport rates increase, the challenge shifts to real-time, precise capture and quantification of reduction products at micromolar levels—such as CO, CH₄, C₂H₄, and liquid products like HCOOH or CH₃OH. This demands evaluation systems that not only offer high gas-tightness in a closed-loop circulation but also achieve deep integration of online sampling with chromatographic or mass spectrometric analysis, ensuring that every photon utilized finds its corresponding “energy destination” in the product. Looking ahead, research on PEC CO₂ reduction is gradually shifting focus from the “serendipitous discovery” of novel, high-efficiency catalysts toward “rational control” of multi-field coupling mechanisms. By integrating automated, digitalized platforms such as the PEC2000, scientists can analyze carrier transport dynamics at heterojunction interfaces and active catalytic sites with millisecond resolution. This progression—from standardizing experimental conditions to achieving precise data output—not only shortens the transition from laboratory research to industrial pilot scale but also lays a scientific foundation for establishing a solar-driven, low-carbon, circular industrial system. In this relay of reconstructing the carbon cycle, precision instrumentation no longer serves merely as an auxiliary tool but functions as the standard of measurement itself on the path to truth.”
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