Solar Fuels Research Articles

Progress on Si‐based photoelectrodes for industrial production of green hydrogen by solar‐driven water splitting

AbstractSolar power has been regarded as the ultimate green‐energy source because of its inexhaustibility and eco‐friendliness. The solar‐driven water‐splitting technology for green hydrogen production is considered to be one of effective ways for solar energy harvesting and storage, which may provide solutions for the energy crisis and environmental issues. In the past decades, great progress has been achieved in this area. Photoelectrochemical (PEC) water splitting is especially promising for the production of solar fuels because of expected large‐scale industrial application. Silicon (Si), as an ideal candidate for the photoelectrode, is the most suitable material for the PEC device in industrial photocatalytic water splitting because of its abundance, mature fabrication technology, and suitable band gap. Here, we give a systematic review on the recent progress for Si‐based photoelectrodes for water splitting with a focus on the industrial application. Particularly, the strategies, such as band‐alignment control, morphology design, and surface engineering, are summarized to enhance the PEC performance and durability for practical application. Furthermore, the perspective for the design of commercial Si‐based PEC devices with high PEC performance, long‐term stability, large‐size, and low cost are given at the end, which shall guide the development of PEC water splitting for industrial application.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels

Photocatalytic CO2 reduction serves as an important technology for value‐added solar fuel production; however, it is generally limited by interfacial charge transport. To address this limitation, a two‐dimensional/two‐dimensional (2D/2D) p‐n heterojunction CuS‐Bi2WO6 (CS‐BWO) with highly connected and matched interfacial lattices was designed via a two‐step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p‐n heterojunction promoted electron transfer from the Cu to Bi sites, leading to coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in BWO nanosheets facilitated the adsorption and activation of CO2, and generation of high‐coverage key intermediate b‐CO32‐, while broad light‐harvesting CuS (CS) provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p‐n heterojunction CS‐BWO exhibited CO and CH4 yields of 135.7 and 62.5 µmol g‐1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS‐BWO nanosheets. This work provided an innovative design strategy for developing high‐activity heterojunction photocatalyst for converting CO2 into value‐added solar fuels.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels.

Photocatalytic CO2 reduction serves as an important technology for value-added solar fuel production; however, it is generally limited by interfacial charge transport. To address this limitation, a two-dimensional/two-dimensional (2D/2D) p-n heterojunction CuS-Bi2WO6 (CS-BWO) with highly connected and matched interfacial lattices was designed via a two-step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p-n heterojunctionpromotedelectron transfer from the Cu to Bi sites, leading to coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in BWO nanosheets facilitated the adsorption and activation of CO2, and generation of high-coverage key intermediate b-CO32-, while broad light-harvesting CuS (CS)provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p-n heterojunction CS-BWO exhibited CO and CH4 yields of 135.7 and 62.5 µmol g-1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS-BWO nanosheets. This work provided an innovative design strategy for developing high-activity heterojunction photocatalyst for converting CO2into value-added solar fuels.

Failure Mechanism Analysis and Emerging Strategies for Enhancing the Photoelectrochemical Stability of Photoanodes.

The development of efficient and stable photoanode materials is essential for driving the possible practical application of photoelectrochemical water splitting. This article begins with a basic understanding of the fundamentals of photoelectrochemical devices and photoanodes. State-of-the-art strategies for designing photoanodes with long-term stability are highlighted, including insertion of hole transport layers, construction of protective/passivation layers, loading of co-catalysts, construction of heterojunctions, and modification of the electrolyte. Based on the insights gained from these effective strategies, we present an outlook for addressing key aspects of the challenges of stabilizing photoanodes development in the future work. Widespread adoption of stability assessment criteria will facilitate reliable comparisons of results from different laboratories. In addition, deactivation of photoanode is defined as a 50 % reduction in productivity. An in-depth understanding of the deactivation mechanism is essential for the design and development of efficient and stable photoanodes. This work will provide insights into the stability assessment of photoanode and facilitate the production of practical solar fuels.

Multifunctional TiO2(R)/Fe2O3 Photocatalytic Composites Obtained from Ilmenite Ore

AbstractThe commercialization of the photocatalysis technology requires that the synthesis of the photocatalytic material is easy to scale up. Thus, the synthesis from earth‐abundant minerals represents one plausible solution to obtain materials by a scalable process with a lower environmental impact. So far, the most promising photocatalyst for this application is titanium dioxide (TiO2), which can be obtained from ilmenite ore; however, its synthesis usually implies toxic solvents and complicated reaction conditions. Thus, here is proposed an optimized method to extract higher amounts of TiO2 by a multivariable Plackett‐Burman design of experiments considering the mass of the ore precursor, the addition of phosphoric acid (H3PO4), the digestion temperature, the amount of base to adjust the pH, and the final thermal treatment. From this design, it was possible to minimize the heat treatment and the amount of base used to favor higher TiO2 (rutile) content with the presence of additional phases of iron oxides (Fe2O3) that act as co‐catalyst to enhance the photocatalytic activity. The photocatalytic activity of the TiO2/Fe2O3 composites obtained was investigated in four model reactions to obtain solar fuels (H2 evolution and CO2 reduction) and to remove endocrine water pollutants (bisphenol A and dyeing water), using visible and natural solar irradiation, respectively.

Boosted Solar Thermochemical Low-Temperature CO2 Splitting On Pt/CeO2 by Interface Catalysis.

Solar thermochemical CO2 splitting using metal oxides is considered as a promising approach to produce solar fuels since it is capable to tap abundant sunlight directly and store solar energy in the renewable fuel. It remains a grand challenge to achieve highly efficient CO2 splitting at low temperature (<800 °C) due to insufficient activation of metal oxides for CO2. Herein, the introduction of a small amount of Pt was found to be able to greatly increase the performance of CO2 splitting with the highest peak CO production rate of about 65 mL min-1 g-1, CO productivity of about 53 mL g-1, nearly 100 % CO2 conversion and long-term stability for 0.5Pt/CeO2, which exceeded most of the state-of-the-art transition metals-based oxides even at lower temperature (700 °C). This could be attributed to the addition of Pt leading to the formation of an interface (Pt0-Ov-Ce3+) after CH4 reduction, which improved CO2 activation and dissociation due to beneficial breakage of C=O bond by the cooperation of Pt0 and oxygen vacancies in the interface.

Addressing challenges for operating electrochemical solar fuels technologies under variable and diurnal conditions

The outdoor operation of electrochemical solar fuels devices must contend with challenges presented by the cycles of solar irradiance, temperature, and other meteorological factors. Herein, we discuss challenges associated with these fluctuations presented over three timescales, including the effects of diurnal cycling over the course of many days, a single diurnal cycle over the course of hours, and meteorological phenomena that cause fluctuations on the order of seconds to minutes. We also highlight both reaction-independent and reaction-specific effects of variable conditions for the hydrogen evolution reaction and CO2 reduction reaction. We identify key areas of research for advancing the outdoor operation of solar fuels technology and highlight the need for metrics and benchmarks to enable the comparison of diurnal studies across systems and geographical locations.

Efficient Computation of Radiative Heat Recovery from Porous Ceramic Monoliths for Efficient Solar Thermochemical Fuel Production

Solar thermochemical hydrogen (STCH) produced by heat-driven water-splitting is a promising route for producing green hydrogen and other zero-emission synfuels. However, the efficiency of STCH must be dramatically increased for it to make an impact on decarbonization efforts. We have previously presented a novel Reactor Train System (RTS) for significantly increasing the efficiency of STCH by employing heat recovery from the redox material and efficient gas exchange processes. In this paper we present a higher-fidelity model for the RTS that accommodates the slow heat diffusion through the STCH redox material. For this purpose, a novel method is introduced for transient modelling of radiative heat in participating media. This method, called GREENER: Generalized Radiation Exchange Factors and Net Radiation, combines the accuracy of Monte Carlo Ray Tracing with the low computational cost of the P1 or Rosseland diffusion approximations. Along with STCH, GREENER has application for modelling volumetric solar receivers, high temperature heat recovery systems like heat exchangers and regenerators, and packed bed reactors. Using the GREENER method, the RTS counterflow radiative heat exchanger is shown to achieve heat recovery effectiveness greater than 70%. The performance of non-uniform porous redox morphologies is evaluated, and high-performing configurations are identified.

Designing 1-nm-Thick MOF Nanosheets with Donor-Acceptor Complexes for Photosynthesis of H2O2 Using Water and Dioxygen Only.

Artificial photosynthesis of hydrogen peroxide (H2O2) presents a promising environmentally friendly alternative to the industrial anthraquinone process. This work designed ultrathin metal-organic framework (MOF) nanosheets on which porphyrin ligand as an electron donor (D) and anthraquinone (AQ) as an electron acceptor (A) are integrated as the D-A complexes. The porphyrin component allows the MOF nanosheets to absorb full-spectrum solar light while the acceptor AQ motif promotes central aluminum ion coordination, hindering layer stacking to achieve a thickness of 1.0 nm. The ultrathin D-A design facilitates the separation of electrons from the MOF skeleton to the AQ motif, which induces the direct two-electron oxygen reduction reaction (ORR) mediated by the reversible redox couple of AQ-AQH2 and multielectron water oxidation reaction (WOR) driven by holes remaining on the porphyrin part. In O2-saturated water, the ultrathin MOF nanosheets outperformed the AQ-free bulk and multilayered counterparts by 2.9 and 2.6 times in H2O2 production, respectively, achieving the apparent quantum yield of 4.8% at 420 nm. It also surpasses other benchmark photocatalysts, including the typical MOF photocatalyst, MIL-125-NH2, and organic polymeric photocatalysts. The ultrathin D-A MOF photocatalyst generated H2O2 via both two-electron ORR as a major path and two-electron WOR as a minor path. This approach presents a promising strategy for the rational design of efficient nanostructured photocatalysts for solar fuels and chemicals.

Natural AIEgens as Ultraviolet Sunscreens and Photosynergists for Solar Fuel Production.

Bio-nano hybrids (BNH), combining semiconductors and microorganisms, have shown great promise for effective solar-to-fuel energy conversion. However, the high-energy ultraviolet (UV) photons in the solar spectrum can cause severe photocorrosion of semiconductors and irreversible photodamage to microorganisms within BNH. Here, we developed an encapsulation strategy using natural luminogens with aggregation-induced emission characteristics (AIEgens) to construct a protective layer for BNH, effectively shielding them against high-energy UV photons. We incorporated natural berberine (BBR) into the BNH composed of Methanosarcina barkeri and polymeric carbon nitrides (CNx). The self-assembled BNH-BBR system displayed a 2.75-fold higher CH4 yield than BNH under simulated solar irradiation. Mechanism analysis revealed that BBR acted as a UV sunscreen for BNH by converting high-energy short wavelengths into low-energy long wavelengths, thereby reducing the accumulation of reactive oxygen species and alleviating the photocorrosion of CNx. Furthermore, BBR functioned as a photosynergist for BNH by regulating photoelectron production and utilization, enhancing the intracellular energy formation in M. barkeri for growth and metabolism. This work provides important insights into the effective and scalable conversion of CO2 into valuable biofuels with BNH under light illumination containing high-energy photons.

Coordinated planning and operation of PV- hydrogen integrated distribution network incorporating daily-seasonal green hydrogen storage and EV charging station

The current study introduces an optimal planning and operational framework for a Distribution Network (DN) that integrates Photovoltaic (PV)-green Hydrogen (H2)-based energy system with Electric Vehicle Charging Station (EVCS). An efficient operational strategy is proposed considering both short-term H2 storage (STHS) and long-term H2 storage (LTHS), ensuring uninterrupted power supply. Besides, a novel Improved Harris Hawk Optimization method is developed to enhance the global search capabilities and convergence rate in optimizing the capacity of Solar module, Electrolyzer, and Fuel cells. The objective of the proposed model is to minimize the device costs, energy loss, and carbon emissions, adhering to all operational constraints. The proposed work is tested on 33-bus radial DN and 51-bus real Indian DN considering the time frame of 10 years. The analysis reveals that the PV-STHS-LTHS configuration, reduces total planning costs by 12% and 15% as compared to the base case in the 33-bus and 51-bus systems, respectively. Additionally, the integration of both daily and seasonal storage facilities with PV systems leads to a reduction in carbon emissions by 76% and 81% in the 33-bus and 51-bus systems, respectively. Besides the carbon reduction, the incorporation of daily and cross-seasonal H2 storage increases oxygen release into the environment by 13% for the 33-bus system and 15% for the 51-bus system.

Fluorination effects on photoisomerization dynamics of azobenzene

The photoisomerization dynamics of azobenzene (Azo-H) and its modulation by electron-withdrawing groups (EWGs) are important for designing photophysical applications, such as artificial muscles, liquid crystal displays, and solar thermal fuels. In this study, the electron-withdrawal kinetics of fluorination and the tailoring of the photoisomerization dynamics of azobenzene were explored using theoretical multiscale simulations. First-principle calculations provide insight into the mechanical aspects of photoisomerization, whereas molecular dynamics simulations offer a time-dependent perspective. Fluorinated azobenzene (Azo-F) exhibits superior photoisomerization responsiveness owing to changes in its molecular conformation and energy states induced by the EWG. These thermodynamic advantages were influenced by the stabilization of the molecular orbitals near the diazene groups. Despite the thermodynamic advantages of Azo-F, heavy fluorine atoms reduce the actuating force and work capacity owing to their increased inertia. This study provides a comprehensive understanding of photoisomerization kinetics modulated by the local fluorination of Azo-H.

Synthesis of a TBA‐Based Polymeric Photocatalyst for Boosting the Selective Bio‐Reduction of Furfural Under Solar Light Illumination

AbstractPhotocatalyst‐enzyme coupled system for harnessing solar light stands out as a highly promising avenue that facilitates bio‐transformation and produces solar fuels. This study explores the integration of a metal‐free photocatalyst in the bio‐reduction of furfural to produce furfuryl alcohol. However, the bio‐reduction of furfural to produce furfuryl alcohol faces challenges due to harsh reaction conditions and expensive catalysts. Likewise, photocatalysts confront various research obstacles, including the absence of long‐lasting photogenerated charge carriers (electrons and holes), stability, and reusability. This work introduces an eco‐friendly and benign catalytic system, featuring an easily prepared photocatalyst using TBA (2,4,6‐tribromo aniline) by standard Ullman coupling. The newly designed polymeric tribromo aniline (PTBA) is cost‐effective, with outstanding light harvesting characteristics, appropriate energy band gap, and remarkably enhanced ability for transfer and migration of photo‐generated carriers. The research aims to optimize parameters for efficient conversion of furfural to produce furfuryl alcohol and also the photocatalytic production of NADH (80.08 %) from consumed NAD+. The photocatalytic efficiency was estimated by the yield percentage of this organic transformation. The absence of metals in the photocatalyst enhances sustainability, showcasing its potential in the green synthesis of furfuryl alcohol which is a valuable chemical with diverse applications.

Interface engineering on single-atom Cu-modified BiOBr1−xClx for efficient artificial photosynthesis of methanol

Converting CO2 into value-added fuels was an attractive way to alleviate the energy crisis. Cu-based catalysts were recognized as the most effective candidates for catalyzing CO2 to solar fuels due to their specific electronic structure. However, selective production of desired fuels from photocatalytic CO2 reduction remained a grand challenge. Herein, the interface engineering of single-atom Cu with BiOBr1−xClx nanosheets (Cu-SA/BOBC) was demonstrated to address this challenge. The single-atom Cu in BOBC favored charge transition, carrier separation, and photon utilization, with a superior performance of CO2 photoreduction yielding CH3OH of 8.21 μmol·g−1·h−1, 94.3 % electron-based CH3OH selectivity. Meanwhile, it could lower the CO2 activation energy barrier, and be conducive to strong CO* adsorption and subsequent hydrogenation of CO* to CHO*, which was critical for the high selectivity of CH3OH. This work highlighted a new insight into regulating the photoreduction of CO2 to CH3OH by interfacial interaction.

Charge Transfer Kinetics and Thermodynamics Control the Energy Conversion Efficiency of a Gallium Phosphide Solar Hydrogen Photocathode.

P-type gallium phosphide (GaP) photocathodes for hydrogen evolution from water have a theoretical energy conversion efficiency of 12% based on the 2.4 eV optical band gap of the material. The performance of actual GaP photocathodes is much lower, for reasons not entirely clear. Here we use vibrating Kelvin probe surface photovoltage (VKP-SPV), open circuit potential (OCP) measurements, and photoelectrochemical (PEC) experiments to evaluate the kinetic and thermodynamic factors that control energy conversion with GaP photocathodes for the hydrogen evolution reaction (HER). We find that the open circuit photovoltage of the bare GaP-H2O junction is limited by recombination at surface states and that an CdS overlayer increases both photovoltage and photocurrent due to formation of a n-p-junction. An optimized GaP/CdS/Pt photocathode drives hydrogen evolution with a quantum efficiency of 62% at 400 nm and 0.0 V RHE and an open circuit photovoltage of 0.43 V at 250 mW cm-2. The Pt cocatalyst increases the photocurrent due to improve HER kinetics but reduces the photovoltage by promoting recombination. Added hydrogen or oxygen gas raise or lower the photovoltage by modifying the electrostatic barrier (band bending) in GaP. This shows that the GaP/CdS junction is not "buried" but behaves like a Schottky junction whose charge separating properties are controlled by the electrochemical potential of the electrolyte. The dynamic junction properties need to be considered in the design of optimized hydrogen evolution photoelectrodes and photocatalysts. Additionally, the work reveals that PEC or OCP measurements tend to underestimate the photovoltage because they do not account for changes in the electrochemical potential at the electrode-liquid contact. In contrast, the VKP-SPV method provides the open circuit photovoltage value directly. By combining the photovoltage data with OCP data, the minority carrier electrochemical potential at the electrode-liquid contact can be measured in a contactless way. This provides an improved understanding of illuminated photoelectrodes for the production of solar fuels.

Hierarchical Ag3VO4 Nanorods as an Excellent Visible Light Photocatalyst for CO2 Conversion to Solar Fuels

The potential of photocatalytic CO2 conversion is significant for the production of fuels and chemicals, while simultaneously mitigating CO2 emissions and addressing environmental concerns. Despite the current drawbacks of single metal-based photocatalysts, such as lower performance, uncontrollable selectivity, and instability, this study focuses on the synthesis of Ag3VO4 nanorods using the sol–gel method. The goal is to create a highly effective catalyst for visible light-responsive CO2 conversion. The successful synthesis of Ag3VO4 nanorods with a nanorod structure, functional under visible light, resulted in the highest yields of CH4 and dimethyl ether (DME) at 271 and 69 µmole/g-cat, respectively. The optimized Ag3VO4 nanorods demonstrated performance improvements, with CH4 and DME production 6.4 times and 4.5 times higher than when using V2O5 samples. This suggests that Ag3VO4 nanorods facilitate electron transfer to CO2, offer short pathways for electron transfer, and create empty spaces within the nanorods as electron reservoirs, enhancing the photoactivity. The prolonged stability of Ag3VO4 in the CO2 conversion system confirms that the nanorod structure provides controllable selectivity and stability. Therefore, the fabrication of nanorod structures holds promise in advancing high-performance photocatalysts in the field of photocatalytic CO2 conversion to solar fuels.

The physical chemistry of solar fuels catalysis

The physical chemistry of solar fuels catalysis

Studying the productivity of sewage sludge (SS) components for photocatalytic CO2 transformation to CO and methane

AbstractEnergy-efficient photocatalytic CO2 conversion to sustainable solar fuels is a promising approach for simultaneously resolving energy and environmental concerns. The increased growth of sewage sludge necessitates research and innovation to propose more commercially viable options for lowering the socioeconomic and environmental complications associated with its current treatment. Sewage sludge can be applied to valuable products or used as a feedstock for energy production. According to the characterization results, the sewage sludge contains several metallic oxides (M), including Ni, Al, Mn, and Cu, and semiconductors (Fe2O3 and ZnO). According to the proposed mechanism, ZnO acts as an electron conductor between the Fe2O3 and the active sewage sludge due to forming an n–n type heterojunction. Under visible-light irradiation, photocatalytic CO2 reduction of sewage sludge was investigated using a fixed bed reactor. The CO2 reduction produced CO and CH4, with production rates of 9.76 and 4.20 µmol g−1 h−1, respectively, via the electrical conductivity in the sewage sludge elements. Furthermore, the impacts of photocatalyst loading, system reforming, light effect and pressure range were examined, where the methane yield at 0.1 g was 4.23 and 2.26 times significantly higher than at 0.05 and 0.2 g, correspondingly. With catalyst loadings of 0.1 and 0.2 g, the mono-oxide productivity was 1.69 and 2.58, notably greater, respectively. Moreover, the best yield of the CO and methane was obtained by using 0.3 bar as pressure and 10% methanol in H2O/CO2 as a reducing agent. Finally, using sewage sludge to produce a solar fuel based on the presence of active metallic oxide and semi-conductor heterojunctions provides novel insights from molecular and engineering perspectives into converting CO2 to a green fuel using wastewater sludge. Graphical abstract

Photocatalytic CO2 Reduction to Solar Fuels by a Chemically Stable Bimetallic Porphyrin-Based Framework.

Porphyrin-based photocatalysts have emerged as promising candidates for facilitating carbon dioxide (CO2) reduction due to their exceptional light-harvesting properties. However, their performance is hindered by complex synthesis procedures, limited structural stability, inadequate CO2 activation capabilities, and a lack of comprehensive structure-property relationships. This study investigates the performance of a porphyrin-based bimetallic framework, [Cu(TPP)Cu2Mo3O11] (TPP = tetrapyridylporphyrin), termed MoCu-1 for photocatalytic CO2 reduction. In addition to its straightforward one-pot synthesis method, the framework shows remarkable chemical stability, particularly notable in alkaline reaction conditions, making it a compelling option for sustainable catalytic applications. By harnessing the superior photoabsorption properties of the porphyrin linker and the abundance of catalytic sites provided by the bimetallic structure, this framework exhibits the potential for enhancing CO2 reduction efficiency. MoCu-1 demonstrates excellent activity in converting CO2 into CO, achieving a maximum yield of 3.21 mmol g-1 with a selectivity of ∼93%. We unravel the intricate interplay of structural features and catalytic activity through systematic characterization techniques and an in situ diffuse reflectance Fourier transform study, which provided insights into the mechanism governing CO2 conversion and was supported by density functional theory calculations. This work contributes to advancing our understanding of photocatalytic processes and offers guidance for designing robust materials for CO2 utilization in renewable energy applications.

The Development of Metal-Free Porous Organic Polymers for Sustainable Carbon Dioxide Photoreduction.

A viable tactic to effectively address the climate crisis is the production of renewable fuels via photocatalytic reactions using solar energy and available resources like carbon dioxide (CO2) and water. Organic polymer material-based photocatalytic materials are thought to be one way to convert solar energy into valuable chemicals and other solar fuels. The use of porous organic polymers (POPs) for CO2 fixation and capture and sequestration to produce beneficial compounds to reduce global warming is still receiving a lot of interest. Visible light-responsive organic photopolymers that are functionally designed and include a large number of heteroatoms and an extended π-conjugation allow for the generation of photogenerated charge carriers, improved absorption of visible light, increased charge separation, and decreased charge recombination during photocatalysis. Due to their rigid structure, high surface area, flexible pore size, permanent porosity, and adaptability of the backbone for the intended purpose, POPs have drawn more and more attention. These qualities have been shown to be highly advantageous for numerous sustainable applications. POPs may be broadly categorized as crystalline or amorphous according to how much long-range order they possess. In terms of performance, conducting POPs outperform inorganic semiconductors and typical organic dyes. They are light-harvesting materials with remarkable optical characteristics, photostability, cheap cost, and low cytotoxicity. Through cocatalyst loading and morphological tweaking, this review presents optimization options for POPs preparation techniques. We provide an analysis of the ways in which the preparative techniques will affect the materials' physicochemical characteristics and, consequently, their catalytic activity. An inventory of experimental methods is provided for characterizing POPs' optical, morphological, electrochemical, and catalytic characteristics. The focus of this review is to thoroughly investigate the photochemistry of these polymeric organic photocatalysts with an emphasis on understanding the processes of internal charge generation and transport within POPs. The review covers several types of amorphous POP materials, including those based on conjugated microporous polymers (CMPs), inherent microporosity polymers, hyper-crosslinked polymers, and porous aromatic frameworks. Additionally, common synthetic approaches for these materials are briefly discussed.