Photoelectrochemical Catalysis Research Articles

Facile Synthesis of Selenium Nanoparticles for Enhanced Oxygen Evolution Reaction: Insights into Electrochemical and Photoelectrochemical Catalysis.

Implementing a hydrogen economy on an industrial scale poses challenges, particularly in developing cost-effective and stable catalysts for water electrolysis. This study explores the catalytic potential of selenium nanoparticles (Se-NPs) synthesized via a simple chemical bath deposition method for electrochemical and photoelectrochemical (PEC) water splitting. The successful fabrication of Se-NPs on fluorine-doped tin oxide (FTO) electrodes has been confirmed using a wide range of analytical tools like X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. Importantly, electrochemical measurements revealed superior electrocatalytic activity of the modified Se-NPs/FTO electrodes, with low overpotential (220 mV at 10 mA cm-2) and Tafel slope (90.13 mV dec-1), indicating faster reaction kinetics and reduced energy inputs for oxygen evolution reaction. Furthermore, the Se-NPs/FTO electrode was employed for PEC water splitting in Na2S electrolyte, showing a notable enhancement in photocurrent density with a difference of 700 μA cm-2 between light and dark conditions at 1.5 V vs RHE, demonstrating efficient light-driven hydrogen production. The overall findings of this work establish that the proposed Se-NPs/FTO electrodes are promising composites for both electrochemical and PEC performance, thereby providing insights into developing cost-effective catalysts for large-scale water splitting.

Operando Electrochemical Raman Spectroscopy Studies of Working Electrodes in (photo)Electrocatalytic Water Splitting

Raman spectroscopy has been applied as a vibrational spectroscopic technique in the field of chemical, materials, and life sciences. Recently, the operando electrochemical Raman spectroscopy has received more research attention for the characterizations of working electrodes in (photo)electrochemical catalysis. This technique allows for the characterization of the fate of electrocatalysts on the surface of the working electrodes under electrochemical reaction conditions, which is crucial to determine the chemical identify of the electrocatalysts.We apply the operando electrochemical Raman spectroscopy to study the anodes and cathodes in the (photo)electrocatalytic water splitting process, which is an important process to generate the clean energy hydrogen (H2) gas from water using solar energy and electricity. Specifically, we study the stability of the electrocatalyst molybdenum sulfide (MoS2) on silicon (Si) photocathode for the hydrogen evolution reaction (HER) and the electrochemical transformation of the electrocatalyst cobalt hydroxide (Co(OH)2) on nanostructured gold (Au) photoanode for the oxygen evolution reaction (OER). We have identified the correlation between the morphological changes and vibrational features of the MoS2 layer and detected the potential-dependent vibrational features of the Co(OH)2 film.

Synergistic vacancy defects and the surface hydrophobic-to-superhydrophilic wetting engineering in W/S co-doped BiOI for enhanced photocatalytic hydrogen evolution

Bismuth oxyhalide (BiOI) has been used for photoelectrochemical catalysis in the field of catalytic hydrogen evolution, but it in a single-phase form has hardly been reported for photocatalytic hydrogen evolution reaction (PHER). Herein, we designed a W/S co-doped BiOI-based superhydrophilic catalyst with oxygen vacancy-rich defects and heterovalent valence states for efficient PHER under visible light. The W/S doping in BiOI not only adjusts the energy band structure and expands the visible light response range, but also transforms its hydrophobicity into superhydrophilicity, with which the gas bubble amount can be reduced and PHER activity enhanced. The introduction of sulfur regulates the content of oxygen vacancies which enhance the active surface sites for capturing water molecules and activating the H-O-H bond. The added tungsten exists in different valence states of W6+ and W5+ which is beneficial for electron hopping and PHER activity. The W/S-BiOI-3 with the suitable W/S doping content exhibits the highest visible-light PHER rate of 9.46 mmol·g−1·h−1, with an apparent quantum efficiency (AQE) of 9.7 % at 420 nm. W/S-BiOI-3 shows excellent PHER activity, stability, and durability, which provides a feasible scheme for other bismuth-based halogen oxides to be used in PHER.

Heterojunction characteristics and photoelectrochemical performance of TiO2 nanorods sensitized by zeolitic imidazolate framework

Traditional photocatalysts suffer from inferior utilization of solar light. Therefore, developing novel photocatalyst for better solar light harvesting is much required in the wake of current environmental problems arising from conventional energy technologies. Here we report synthesis and characterization of photocatalysts based on TiO2 nanorods (TNR) and Zeolitic Imidazolate Framework-9 (ZIF-9) and their photoelectrochemical properties. The TNRs were sensitized by ZIF-9 through solvothermal method. The presence of ZIF-9 on TNR formed a p-n heterojunction which assisted in initiating efficient charge separation and promoting injection of these carriers into the electrolyte. The heterojunction catalysts also exhibited enhanced optical properties in terms of extended absorption with reduced bandgap in comparison to the TNR film. The aforementioned properties manifested in improved photoelectrochemical performance with a current density of 0.94 mA/cm2, which is four times better than TNR and an applied bias photon to current efficiency (ABPE) of 0.27 %, which is five times better than TNR film alone. These superior properties of the processed ZIF-TNR demonstrate their potential for photoelectrochemical catalysis, thus paving the way for green hydrogen generation.

Frontiers in Photoelectrochemical Catalysis: A Focus on Valuable Product Synthesis.

Photoelectrochemical (PEC) catalysis provides the most promising avenue for producing value-added chemicals and consumables from renewable precursors. Over the last decades, PEC catalysis, including reduction of renewable feedstock, oxidation of organics, and activation and functionalization of C─C and C─H bonds, are extensively investigated, opening new opportunities for employing the technology in upgrading readily available resources. However, several challenges still remain unsolved, hindering the commercialization of the process. This review offers an overview of PEC catalysis targeted at the synthesis of high-value chemicals from sustainable precursors. First, the fundamentals of evaluating PEC reactions in the context of value-added product synthesis at both anode and cathode are recalled. Then, the common photoelectrode fabrication methods that have been employed to produce thin-film photoelectrodes are highlighted. Next, the advancements are systematically reviewed and discussed in the PEC conversion of various feedstocks to produce highly valued chemicals. Finally, the challenges and prospects in the field are presented. This review aims at facilitating further development of PEC technology for upgrading several renewable precursors to value-added products and other pharmaceuticals.

Synergistic Photoredox and Electrochemical Catalysis in Organic Synthesis and Late‐Stage Functionalizations

AbstractThis review delves into the innovative field of interfacial photoelectrochemical (iPEC) and photoelectrochemical (PEC) catalysis, the dynamic synthesis methodologies that seamlessly integrates electrochemical and photoredox catalysis for efficient and environmentally friendly reactions. Utilizing minute quantities of photocatalysts, visible light becomes a powerful tool, generating transient excited states to catalyze a spectrum of reactions through single‐electron oxidation or reduction events. The review categorizes recent advancements, highlighting applications in organic synthesis, late‐stage modifications, and the distinctive features of photoelectrochemical methodology. Despite being in its early stages, this synergistic approach holds great promise for propelling organic synthesis forward, with potential applications in large‐scale synthesis and diverse late‐stage functionalizations, including asymmetric catalysis and bioconjugation strategies for biomolecule modifications.

Photoelectrochemical-driven nitrogen reduction to ammonia by a Vo-SnO2/TiO2 composite electrode.

N2 molecules with the NN triple bond structure are difficult to cleave under mild conditions to achieve the nitrogen fixation reaction. Photoelectrochemical (PEC) catalysis technology combining the advantages of photocatalysis and electrocatalysis provides the possibility of the nitrogen reduction reaction under ambient conditions. Herein, an SnO2/TiO2 photoelectrode was first fabricated through depositing SnO2 quantum dots on TiO2 nanorod arrays via a simple hydrothermal method. The oxygen vacancy (Vo) content was then induced in SnO2 through annealing SnO2/TiO2 at high temperature under an inert atmosphere. The heterogeneous structure of Vo-SnO2 quantum dots and TiO2 nanorods boosted the separation of photocarriers. The photoelectrons generated by photoexcitation were transferred from the conduction band of TiO2 to the conduction band of Vo-SnO2 and trapped by Vo. Vo activates N2 molecules adsorbed on the catalyst surface, and reacts with H+ in the electrolyte to generate NH3. The nitrogen fixation yield of PEC catalysis and its faradaic efficiency can reach 19.41 μg cm-2 h-1, and 59.6% at -0.2 V bias potential, respectively. The heterogeneous structure of Vo-SnO2/TiO2, introduction of Vo and synergistic effect between light and electricity greatly promotes the PEC nitrogen reduction to NH3.

One‐Step Electrochemical Fabrication of 3D Gold Nanotrees with Enhanced Broadband Plasmonic Excited Carriers for Photoelectrochemical Reactions

AbstractPlasmonic nanostructures that generate hot carriers and induce catalytic chemical transformations are ideal candidates for solar energy utilization. However, the existing nanostructures require multistep synthesis procedures and generate fewer hot carriers due to their narrow resonance region and limited hotspots, restricting their usage in plasmonic catalysis. Inspired by the light‐harvesting behavior of the trees, the current work reports a one‐step fabrication strategy via electrodeposition for direct anisotropic growth of the 3D gold nanotrees with tunable size, branches, and height. The as‐synthesized nanostructures with broadband light absorption and plentiful hotspots can significantly foster hot carrier generation. The improved hot electron generation of 3D gold nanotrees is confirmed by in situ surface‐enhanced Raman spectroscopy for the dimerization reaction of 4‐nitrothiophenol. The energetic hot holes generated by the 3D gold nanotrees facilitate water oxidation and exhibit 18.6 times higher catalytic efficiency than Au film under 625 nm. Meanwhile, the photoelectrochemical catalysis of 3D gold nanotrees shows better performance compared with conventional Au nanospheres. This work opens up a promising avenue for fundamental studies of plasmonic catalysis via a wide variety of 3D gold nanotrees.

Versatile Synthesis of Symmetric and Unsymmetric Imines via Photoelectrochemical Catalysis: Application to N-Terminal Modification of Phenylalanine.

A strategy that combines electrochemical synthesis and photoredox catalysis was reported for the efficient synthesis of imines. This approach was demonstrated to be highly versatile in producing various types of imines, including symmetric and unsymmetric imines, by exploring the impact of different substituents on the benzene ring of the arylamine. Additionally, the method was specifically applied to modify N-terminal phenylalanine residues and was found to be successful in the photoelectrochemical cross-coupling reaction between NH2 -Phe-OMe and aryl methylamines, leading to the synthesis of phenylalanine-containing imines. Therefore, this technique would present a convenient and efficient platform for synthesizing imines, with promising applications in chemical biology, drug development, and organic synthesis.

Enhanced light-driven photoelectrochemical catalysis of water splitting by TiO2 nanotubes grown on acid-etched titanium foils

Titanium dioxide with suitable band edges is one of promising photocatalysts for water splitting. Nanotubes with one-dimensional structure can induce efficient charge transfers and hollow centers can provide large surface area for surface reactions. Modifying Ti foils for anodization can enhance light utilization of TiO2 nanotube photoelectrodes. In this work, it is firstly to fabricate TiO2 nanotube photoelectrodes on acid-etched Ti foils by anodization (MNT) for photoelectrochemical catalyzing water splitting. Different acid-etching durations are applied on Ti foils to induce various rugged surfaces. The resulting photoelectrodes present largely enhanced light utilization than that fabricated by the pristine Ti foil. The anodization duration is also optimized to find suitable lengths of MNT. The smallest overpotential of 524.7 mV at 10 mA/cm2 and Tafel slope of 167 mV/dec are obtained for the optimal MNT photoelectrode. The TiO2 nanotubes grown on the pristine Ti foil shows the overpotential of 679.3 mV at 10 mA/cm2 and Tafel slope of 285 mV/dec. This result opens a blueprint for raising the photocatalytic ability by simply modifying the surface property of the conductive substrate. Other modifications may be applicable to enhance the roughness of Ti foils for growing more efficient MNT array as photocatalysis of water splitting.

Recent Progress and Perspectives on Photocathode Materials for CO2 Catalytic Reduction.

The continuous consumption of fossil energy and excessive emissions of carbon dioxide (CO2) have caused a serious energy crisis and led to the greenhouse effect. Using natural resources to convert CO2 into fuel or high-value chemicals is considered to be an effective solution. Photoelectrochemical (PEC) catalysis utilizes abundant solar energy resources, combined with the advantages of photocatalysis (PC) and electrocatalysis (EC), to achieve efficient CO2 conversion. In this review, the basic principles and evaluation criteria, of PEC catalytic reduction to CO2 (PEC CO2RR), are introduced. Next, the recent research progress on typical kinds of photocathode materials for CO2 reduction are reviewed, and the structure-function relationships between material composition/structure and activity/selectivity are discussed. Finally, the possible catalytic mechanisms and the challenges of using PEC to reduce CO2 are proposed.

Ti–Fe2O3/Ni(OH) as an efficient and durable photoanode for the photoelectrochemical catalysis of PET plastic to formic acid

Ti–Fe2O3/Ni(OH) as an efficient and durable photoanode for the photoelectrochemical catalysis of PET plastic to formic acid

Recent Progress in Interface Engineering of Nanostructures for Photoelectrochemical Energy Harvesting Applications.

With rapid and continuous consumption of nonrenewable energy, solar energy can be utilized to meet the energy requirement and mitigate environmental issues in the future. To attain a sustainable society with an energy mix predominately dependent on solar energy, photoelectrochemical (PEC) device, in which semiconductor nanostructure-based photocatalysts play important roles, is considered to be one of the most promising candidates to realize the sufficient utilization of solar energy in a low-cost, green, and environmentally friendly manner. Interface engineering of semiconductor nanostructures has been qualified in the efficient improvement of PEC performances including three basic steps, i.e., light absorption, charge transfer/separation, and surface catalytic reaction. In this review, recently developed interface engineering of semiconductor nanostructures for direct and high-efficiency conversion of sunlight into available forms (e.g., chemical fuels and electric power) are summarized in terms of their atomic constitution and morphology, electronic structure and promising potential for PEC applications. Extensive efforts toward the development of high-performance PEC applications (e.g., PEC water splitting, PEC photodetection, PEC catalysis, PEC degradation and PEC biosensors) are also presented and appraised. Last but not least, a brief summary and personal insights on the challenges and future directions in the community of next-generation PEC devices are also provided.

Cobalt-Phosphate (Co-Pi)-Modified WO3 Photoanodes for Performance-Enhanced Photoelectrochemical Wastewater Degradation.

Photocatalytic technology, with features of wide applicability, mild reaction conditions and sunlight availability, satisfies the requirements of "green chemistry". As the star photoanode material for photoelectrochemical catalysis, WO3 has a suitable band gap of 2.8 eV and a strong oxidation capacity, as well as displaying great potential in organic wastewater degradation. However, its performance is usually hindered by competition with water oxidation to generate peroxides, rapid charge complexation caused by surface defect sites, and so on. Herein, WO3 films modified with cobalt-phosphate (Co-Pi/WO3) film were prepared and involved in photocatalytic organic wastewater degradation. A degradation rate constant of 0.63311 h-1 was obtained for Co-Pi/WO3, which was much higher than that of WO3, 10.23 times that of direct photocatalysis (DP) and 23.99 times that of electrocatalysis (EC). After three cycles of degradation, the film can maintain a relatively good level of stability and a degradation efficiency of 93.79%.

Fabricating High-Quality Cu2O Photocathode by Magnetron Sputtering: Insight into Defect States and Charge Carrier Collection in Cu2O

Earth-abundant Cu2O comprises one of the best-performing photocathodes for solar-driven water splitting that provides a sustainable solution for the energy crisis. However, typical Cu2O photocathodes based on widespread electrochemical deposition (ED-Cu2O) hit a bottleneck in pursuing higher efficiency due to ED-Cu2O’s inadequate electrical properties and excessive detrimental defects, demonstrating the need to explore alternative methods to fabricate a high-quality Cu2O film for further development of Cu2O photoelectric conversion. Here, commercial magnetron sputtering (MS) is exploited to manufacture a Cu2O photocathode (MS-Cu2O) with an appreciable electrical property and diminished point defects. Comprehensive optoelectronic properties characterization and energy band simulations unveil that the synchronous enhancement in electronic properties and charge carrier lifetime of MS-Cu2O benefiting from its suppressed defects relative to ED-Cu2O synergistically boosts its carrier collection efficiency and PEC performance. This work demonstrates the potential of MS in fabricating an energetic Cu2O photocathode to push the advancement of Cu2O photoelectrochemical catalysis.

Recent Progress in Fabrication and Physical Properties of 2D TMDC-Based Multilayered Vertical Heterostructures

Two-dimensional (2D) vertical heterojunctions (HSs), which are usually fabricated by vertically stacking two layers of transition metal dichalcogenide (TMDC), have been intensively researched during the past years. However, it is still an enormous challenge to achieve controllable preparation of the TMDC trilayer or multilayered van der Waals (vdWs) HSs, which have important effects on physical properties and device performance. In this review, we will introduce fundamental features and various fabrication methods of diverse TMDC-based multilayered vdWs HSs. This review focuses on four fabrication methods of TMDC-based multilayered vdWs HSs, such as exfoliation, chemical vapor deposition (CVD), metal-organic chemical vapor deposition (MOCVD), and pulsed laser deposition (PLD). The latest progress in vdWs HS-related novel physical phenomena are summarized, including interlayer excitons, long photocarrier lifetimes, upconversion photoluminescence, and improved photoelectrochemical catalysis. At last, current challenges and prospects in this research field are provided.

Photoelectrochemical Catalysis of Waste Polyethylene Terephthalate Plastic to Coproduce Formic Acid and Hydrogen

Photoelectrochemical Catalysis of Waste Polyethylene Terephthalate Plastic to Coproduce Formic Acid and Hydrogen

Activating a Semiconductor-Liquid Junction via Laser-Derived Dual Interfacial Layers for Boosted Photoelectrochemical Water Splitting.

The semiconductor-liquid junction (SCLJ), the dominant place in photoelectrochemical (PEC) catalysis, determines the interfacial activity and stability of photoelectrodes, whcih directly affects the viability of PEC hydrogen generation. Though efforts dedicated in past decades, a challenge remains regarding creating a synchronously active and stable SCLJ, owing to the technical hurdles of simultaneously overlaying the two advantages. The present work demonstrates that creating an SCLJ with a unique configuration of the dual interfacial layers can yield BiVO4 photoanodes with synchronously boosted photoelectrochemical activity and operational stability, with values located at the top in the records of such photoelectrodes. The bespoke dual interfacial layers, accessed via grafting laser-generated carbon dots with phenolic hydroxyl groups (LGCDs-PHGs), are experimentally verified effective, not only in generating the uniform layer of LGCDs with covalent anchoring for inhibited photocorrosion, but also in activating, respectively, the charge separation and transfer in each layer for boosted charge-carrier kinetics, resulting in FeNiOOH-LGCDs-PHGs-MBVO photoanodes with a dual configuration with the photocurrent density of 6.08 mA cm-2 @ 1.23 VRHE , and operational stability up to 120 h @ 1.23 VRHE . Further work exploring LGCDs-PHGs from catecholic molecules warrants the proposed strategy as being a universal alternative for addressing the interfacial charge-carrier kinetics and operational stability of semiconductor photoelectrodes.

One-Step Hydrothermal Synthesis of Sulfur Quantum Dots for Photoelectrochemical Catalysis for Dye Degradation

One-Step Hydrothermal Synthesis of Sulfur Quantum Dots for Photoelectrochemical Catalysis for Dye Degradation

In situ localization of BiVO4 onto two-dimensional MXene promoting photoelectrochemical nitrogen reduction to ammonia

The existing industrial ammonia synthesis usually adopts the Haber-Bosch process, which requires harsh conditions of high temperature and high pressure, and consumes high energy. Under this circumstance, photoelectrochemical (PEC) catalysis is regarded as a promising method for N2 reduction reaction (NRR), but bears problems of low efficiency and yield. Thus, exploring active catalysts remains highly desirable. In this work, BiVO4@MXene hybrids have been facilely synthesized by a hydrothermal route. The heterojunctions by the in situ growth of BiVO4 onto two-dimensional (2D) MXene greatly increase the NRR efficiency: under photoelectric conditions, the optimized NH3 yield is 27.25 µg h − 1 cm−2, and the Faraday efficiency achieves 17.54% at −0.8 V relative to the reversible hydrogen electrode (RHE), which are higher than most state-of-the-art NRR (photo) electrocatalysts. The mechanism speculation shows the enhanced light absorption range and the heterojunction formation largely promote the separation and the transfer efficiency of photogenerated carriers, thereby improving the PEC catalytic ability. Therefore, this work provides a hybrid route to combine the advantages of photo and electric catalysis for effective artificial nitrogen fixation.