Amid the wave of energy transition toward carbon neutrality, solar-driven water-splitting hydrogen production technology has long been regarded as a promising solution. However, an undeniable reality remains: the vast majority of photocatalytic research still stays within the laboratory stage. Catalytic materials that perform excellently under simulated light sources, constant temperatures, and pure systems often suffer severe performance degradation when exposed to real sunlight—spectral fluctuation, intensity variation, temperature cycling, and complex environmental factors together form the “first barrier” that hinders the transition from laboratory research to real-world applications.
Traditional photocatalytic research mostly exists at the laboratory level, with very few experiments conducted outdoors. The State Key Laboratory of Crystal Materials at Shandong University reported an integrated solar-driven OWS system in Nature Communications, where five modular outdoor demonstration units were built and tested under natural sunlight for one week. The average solar-to-hydrogen (STH) conversion efficiency reached 1.21%. The photocatalytic system consisted of a hydrogen evolution cell using a halide perovskite photocatalyst ((MoSe₂-loaded CH(NH₂)₂PbBr₃-xIx)) and an oxygen evolution cell based on a BiVO₄ photocatalyst modified with NiFe layered double hydroxide (LDH). These components were bridged through an I₃⁻/I⁻ redox mediator to facilitate electron transfer, achieving overall water splitting with a high solar-to-hydrogen conversion efficiency of 2.47±0.03%. By addressing intrinsic limitations of traditional photocatalytic systems—such as simultaneous hydrogen and oxygen evolution within a single cell and the resulting severe back-recombination—the study introduced a new system design concept, thereby improving both efficiency and practicality.
Figure 1. Schematic diagram of the Z-scheme solar water-splitting system, where H₂ and O₂ production processes are separated. The net reaction involves water decomposition mediated by the I₃⁻/I⁻ redox shuttle to generate H₂ and O₂. HER represents the hydrogen evolution reaction, and OER represents the oxygen evolution reaction. NiFe-LDH/BiVO₄ indicates NiFe-layered double hydroxide-modified BiVO₄. FPBI/MoSe₂ represents MoSe₂-loaded FAPbBr₃-xIx (FPBI, FA=CH(NH₂)₂⁺). CC refers to carbon cloth, and FTO refers to fluorine-doped tin oxide glass.
Figure 2. Synthesis of MoSe₂/FPBI composites. (a) Schematic illustration of the synthesis of FAPbBr₃ (FPB), FAPbBr₃-xIx (FPBI), and MoSe₂/FPBI composites. Dodecahedrons represent perovskite particles, with corresponding structural diagrams shown in bubbles. FA ions are omitted for simplicity. (b) Comparison of XRD patterns of FPB, FPBI, MoSe₂/FPBI composites, and simulated FPB. (c) DRS spectra of MoSe₂, FPB, FPBI, and MoSe₂/FPBI. “a.u.” denotes “arbitrary units.” (d) SEM image of MoSe₂/FPBI; the inset shows SEM of MoSe₂. (e) HR-TEM image of MoSe₂/FPBI, with red and blue boxed insets corresponding to FPBI and MoSe₂, respectively.
Figure 3. Band alignment and carrier dynamics studies. (a) XPS valence band spectra of FAPbBr₃-xIx (FPBI) and MoSe₂. The valence band maximum relative to the normal hydrogen electrode (EVBM, NHE) can be calculated as EVBM, NHE = φ + EVB − 4.44, where φ is the instrument work function (4.20 eV). The calculated EVBM, NHE values for FPBI and MoSe₂ are 1.04 eV and 1.11 eV, respectively. (b) Tauc plots for FPBI and MoSe₂, with band gaps (Eg) of 2.05 eV and 1.14 eV, respectively. The conduction band minimum (ECBM) is derived as ECBM = EVBM − Eg, giving −1.01 eV for FPBI and −0.03 eV for MoSe₂. (c) Schematic of FPBI band structure and redox potentials. (d–e) Single-particle photoluminescence images of FPBI and MoSe₂/FPBI. (f–g) Photoluminescence and time-resolved PL spectra corresponding to particles labeled in (d) and (e). “a.u.” denotes “arbitrary units.”
Figure 4. Large-scale outdoor water-splitting panel system. (a) Schematic of the tandem water-splitting unit. (b) Enlarged view showing HER and OER cells. The top red sheet is a MoSe₂/FAPbBr₃-xIx film (10×10 cm²), and the bottom yellow sheet is a NiFe-LDH/BiVO₄ film (5.5×7 cm²). (c) Image of the outdoor modular setup: a five-unit solar-driven overall water-splitting system. (d–e) Structural layouts of the hydrogen and oxygen sub-reactors. (f) Product yield and corresponding STH data (3-hour cycles, 11:00–14:00). Data collected in Jinan, China (117.0687°E, 36.6795°N) at the State Key Laboratory of Crystal Materials, Shandong University, from October 27 to November 2, 2023. STH efficiency error bars indicate standard deviation from seven measurements. (g) Recorded H₂ evolution rate, STH, and light intensity dependence on the STH peak day — October 29, 2023.
The outdoor water-splitting system reported by Shandong University in Nature Communications was validated under real-world environmental conditions—natural sunlight, diurnal temperature fluctuations, and seasonal variations. The key to such studies lies in stable operation under non-isothermal, non-constant light intensity conditions with meteorological fluctuations. The BOFILAI Solar Photovoltaic Photoelectrocatalytic Reaction System is specifically designed for such real-field photocatalytic research. It supports continuous, automated water-splitting experiments under natural sunlight, covering a temperature range from −10°C to 50°C and accommodating light intensity fluctuations between 200 W/m² and 1000 W/m². The system integrates multiple types of catalytic electrodes and reactor configurations. Whether for Z-scheme dual-cell systems or novel composite catalysts, this platform enables outdoor performance verification and data acquisition.
No.1 Intelligent Sun-Tracking System
The photovoltaic module of the Solar Photovoltaic Photoelectrocatalytic Reaction System is equipped with an irradiation detector that continuously measures solar irradiance and adjusts the tilt angle of the PV panel in real time to maximize solar energy utilization efficiency.
No.2 Efficient Utilization
The system’s plate-type reactor design effectively increases the surface area of catalytic electrodes, enhancing catalyst–reactant contact. Its thin-layer configuration minimizes uneven reactant distribution due to slow diffusion, reduces side reactions, and improves product selectivity. The flow-type system enhances electron and proton transfer rates during catalysis, thereby improving overall reaction efficiency.
No.3 Real-Time Monitoring
The system enables real-time online monitoring of parameters such as irradiance, voltage, current, hydrogen evolution rate, pH, and temperature, allowing researchers to dynamically optimize reaction conditions and performance.
No.4 Graded Circulation
The Solar Photovoltaic Photoelectrocatalytic Reaction System employs micro-pumps to drive liquid flow, ensuring thorough contact between electrolyte and electrodes. Meanwhile, gas pumps at the product outlet efficiently separate and collect gaseous products, improving circulation efficiency and reaction rate.
No.5 Flexible Design
The system can be customized in terms of reactor dimensions, circulation configuration, and monitoring schemes to suit diverse research needs and experimental setups.
Wuhan University of Technology Outdoor Photoelectrocatalytic Platform
The custom photoelectrocatalytic water treatment system at Wuhan University of Technology integrates solar power generation, sun-tracking, electrolysis-based hydrogen production, and fluid management into a comprehensive outdoor photocatalytic research platform.
The intelligent human–machine interface (HMI) of the photoelectrocatalytic water treatment system enables real-time monitoring and recording of key parameters such as photovoltaic power, electrolysis data, and temperature. It supports USB export in CSV format, achieving fully automated data acquisition and preliminary analysis, thus providing a solid data foundation for outdoor catalytic studies.
Toward a Real Energy Future
From laboratory to outdoors, from ideal to real-world conditions, the Solar Photovoltaic Photoelectrocatalytic Reaction System helps researchers bridge the “last mile,” revealing the true performance of materials and systems under complex conditions such as diurnal cycles and weather variations. Only technologies that withstand real outdoor validation truly hold the potential for industrialization.
