Copper (Cu) has been widely recognized as a promising catalyst for electrocatalytic CO2 reduction (CO2R) into value-added multi-carbon (C2+) chemicals. However, the limited selectivity of C2+ products persists due to the inactivation of precisely designed active sites triggered by uncontrollable reconstruction. Herein, we report the successful synthesis of the electrocatalysts of Lewis-acidic aluminum (Al)-doped copper oxides (AlCuOx) with exposed abundant atomic-scale Al u2212 O u2212 Cu sites. The strong Al u2212 O u2212 Cu bridge bonds effectively suppress surface electrochemical reconstruction, and highly stable Cuu03B4+ species are obtained. The AlCuOx catalyst exhibits an excellent electrocatalytic CO2R performance, delivering a Faradaic efficiency (FE) for C2+ products of 73.6% (ethylene 54.16% and ethanol 19.44%), at a current density of u2212 221.7 mA/cm2. The analyses of in situ spectroscopy and theoretical calculations confirm that the high electron localization of Cu active sites in AlCuOx strengthens the interactions between Cu and linearly bonded *CO (*COL) through p u2212 d orbital hybridization, thus facilitating C u2212 C coupling and steering the CO2 electroreduction pathway toward C2+ products. This work provides new insights into constructing reconstruction-resistant Cu-based catalysts that enable efficient and stable CO2-to-C2+ conversion.
Aqueous zinc–iodine batteries (AZIBs) have attracted considerable attention as a promising energy storage technology due to their high safety, low cost, and high theoretical capacity. However, the practical application of AZIBs is hindered by the slow iodine redox kinetics and the severe polyiodide shuttle effect. This work presents a novel trace cobalt-doped carbon cloth-based iodine host cathode (Co–CC/I2) fabricated by a straightforward impregnation–annealing–acid-corrosion process. This strategy eliminates the generation of unstable cobalt nanoparticles and incorporates cobalt atoms into the carbon matrix, ensuring the retention of abundant pore channels along with the creation of numerous active catalytic sites. The Co–CC/I2 cathode integrates the advantages of trap−adsorption−catalysis, effectively suppresses the polyiodides shuttle effect, as well as promotes the reversible conversion of iodine species (I⁻/I0) to improve the electrochemical performance. The Co–CC/I2 cathode exhibits an outstanding rate capability (223.6 and 131.3 mAh/g at 0.5 and 8 A/g, respectively), coupled with a low self-discharge rate over 120 h and a high capacity retention of 94.7
Energy-relevant electrocatalytic reactions, such as hydrogen evolution, oxygen evolution, CO2 reduction, and nitrate reduction, are fundamental to sustainable energy conversion and electrochemical manufacturing. Despite decades of progress, advances in electrocatalysis remain constrained by an incomplete understanding of active sites, reaction kinetics, and the interfacial microenvironment under operating electrochemical conditions. As an in situ characterization technique, scanning electrochemical microscopy (SECM) is well suited to addressing these challenges because of its submicron spatial resolution and rapid temporal response. Although SECM has been widely applied in recent years, reviews that systematically summarize these advances from the perspective of electrocatalytic reactions and their underlying mechanisms remain scarce. To bridge this gap, this review outlines the fundamental principles of SECM and reframes its functional applications in energy-relevant electrocatalysis through a mechanism-oriented framework. Building on recent progress, we highlight the key contributions of SECM in three areas: identification and quantification of active sites, determination of reaction kinetics, and in situ monitoring of the interfacial microenvironment evolution. Furthermore, we discuss several directions that are expected to shape the future development of SECM, including multimodal correlative characterization, integration of experimental measurements with theoretical modeling, innovations in probe technologies, and the extension of SECM applications from model systems to practical devices. These perspectives provide insight into electrocatalytic mechanisms and guide the design of next-generation electrocatalysts.
Internet of Nano-Things (IoNT) drives the need for autonomous energy solutions that can operate under low‑grade, high‑entropy ambient conditions. This review examines coinage metal nanostructures—namely, Au, Ag, and Cu—as multifunctional materials for next‑generation energy‑harvesting platforms. Beyond elemental systems, selected coinage‑metal‑containing compounds are included where they play a direct mechanistic role in energy conversion. These nanostructures exhibit tunable electronic properties, high surface reactivity, and strong coupling phenomena, enabling their integration into diverse transduction mechanisms, including flexoelectric, plasmonic, piezoelectric, thermoelectric, magnetostrictive, and triboelectric systems. Strategies for performance optimization, such as surface functionalization, morphological control, and composite formation, are discussed in relation to interfacial interactions, charge transport, and structural stability. Sustainability considerations, including material availability, recyclability, and scalability, are also addressed. By synthesizing recent advances across material science, nanotechnology, and energy engineering, this review provides a forward‑looking perspective on the design of coinage-metal‑based nanogenerators for self‑powered systems in distributed IoNT environments.
Electrocatalytic CO2 reduction reaction (CO2RR) has achieved remarkable selectivity toward C1 and C2 products; however, the direct electrosynthesis of long-chain (C4+) and structurally complex molecules remains challenging. Coupling CO2 electrolysis with downstream biological, thermal, electrochemical, or organic transformations offers a practical route to produce long-chain and structurally complex compounds, thereby expanding the product spectrum to include fuels, fine chemicals, polymers, and functional materials. In this mini review, we systematically summarize recent progress in four representative cascade configurations: electro–biological, electro–thermal, electro–electro, and electro–organic systems. For each configuration, we discuss the underlying principles, analyze the key coupling challenges, and summarize the corresponding optimization strategies along with representative studies. We further compare the technological features, product scope, and scalability limitations of these cascade systems in terms of reaction condition compatibility, multiphase interface engineering, energy efficiency, and system integration. Finally, we outline future research priorities aimed at accelerating the translation of CO2 cascade technologies from laboratory-scale proof-of-concept studies to industrially relevant platforms.
The environmental challenges posed by the discharge of printing and dyeing wastewater urgently require effective treatment technologies. This study developed an efficient adsorbent through sodium dodecylbenzenesulfonate (SDBS) self-assembled Mg/Al-layered double hydroxides (LDHs) via a one-step hydrothermal method. When an Mg2⁺/Al3⁺/SDBS molar ratio was 3:1:1.40, and calcination was performed at 300 °C for 2 h, the adsorbent achieved a markedly high removal efficiency of 84.8
Although iron-based polyanionic cathodes are promising for use in sodium-ion batteries because of their low cost and high structural stability, their practical application is hindered by low electronic conductivity and sluggish Na+ transport kinetics at high rates. Herein, a molybdate-induced rigid–flexible composite framework strategy is proposed to regulate the polyanionic skeleton of Na3.4Fe2.4(PO4)1.4P2O7 (NFPP)/C. A series of MoO42−-doped NFPP/C cathodes is synthesized via a high-shear mixer-assisted sol–gel method. The optimized Na3.4Fe2.4(PO4)1.3(MoO4)0.1P2O7/C cathode exhibits outstanding electrochemical performance, delivering 101.1 mAh/g after 2000 cycles at 5 C with 97.02
The topological nanopores of covalent organic frameworks (COFs) are promising platforms for constructing photocatalytic nanoreactors for CO2 conversion. However, simultaneously increasing electron density, promoting electron transfer, and enhancing CO2 adsorption and activation within confined nanopore spaces remain critical challenges for boosting photocatalytic performance. Herein, polyhydroxylated fullerene (C60OH) molecules were assembled within the nanopores of a two-dimensional porphyrin-based COF (pCOF) through hydrogen-bonding interactions with the hydroxyl-functionalized 2,5-dihydroxyterephthalaldehyde (DHTA) acceptor units in the pCOF, thereby constructing a C60OH@pCOF photocatalytic nanoreactor featuring DHTA–C60OH molecular heterojunctions. Under full-light irradiation, the optimized C60OH@pCOF achieves a CO production rate of 40.47 μmol/(g·h) in pure water, approximately four times higher than that of pristine pCOF, along with a CO selectivity of 99
Developing high-efficiency, stable bifunctional electrocatalysts for seawater splitting is vitally essential. In this work, we fabricated an amorphous high-entropy FeCoNiMo (FCNM) phosphide bifunctional catalyst on nickel foam (NF) via facile, one-step electrodeposition at room temperature. The obtained FCNMP possessed a three-dimensional porous structure composed of ultrathin nanosheets, which is conducive to providing a large active specific surface area and promoting ion/mass transport during the reaction. The FCNMP/NF electrocatalyst exhibited outstanding electrocatalytic performance in simulated alkaline seawater, requiring the low overpotentials of 287.5 and 201.3 mV for the oxygen evolution reaction and hydrogen evolution reaction, to reach a current density of 50 mA/cm2, respectively. The enhanced catalytic performance was attributed to the synergistic effects of the optimized electronic structure of high-entropy materials, the abundant accessible active sites from the ultrathin nanosheet morphology, and the amorphous structure. Furthermore, when FCNMP/NF was used as the cathode and anode catalysts for seawater splitting, it required only 1.75 V to reach 50 mA/cm2 for overall simulated alkaline seawater splitting. The system operated stably for over 50 h, demonstrating great potential for practical applications. Moreover, the catalyst maintained a favorable electrochemical performance in real alkaline seawater. This study provides a novel strategy for the design of high-performance bifunctional electrocatalysts for alkaline seawater splitting.
In this study, we systematically investigated the role of configurational entropy and morphological control in enhancing the electrocatalytic performance of MXenes for the hydrogen evolution reaction (HER). We successfully synthesized a series of MAX phase precursors with increasing entropy: low-entropy (single-metal) Ti2AlC, V2AlC, Nb2AlC; a medium-entropy solid solution (Ti1/3V1/3Nb1/3)2AlC; and a high-entropy (Ti1/4V1/4Nb1/4Ta1/4)2AlC. X-ray diffraction analysis confirmed the successful formation of layered hexagonal MAX phases and their transformation into MXenes, with characteristic shifts in the (002) reflection indicating interlayer expansion. Scanning and transmission electron microscopies reveal the evolution from dense, plate-like MAX grains to exfoliated, accordion-like multilayered Ti1/2V1/2Nb1/2Ta1/2CTz MXene and sheets with few-layered morphologies, while X-ray photoelectron spectroscopy demonstrates Al removal and the presence of mixed oxidation states for Ti, V, Nb, and Ta. The electrochemical analysis of HER revealed a clear trend of improved activity with increasing entropy. Single-metal MXenes exhibited overpotentials (η@10 mA/cm2) of 231–207 mV and Tafel slopes of 163–155 mV/dec. The medium-entropy (Ti1/3V1/3Nb1/3)2CTz MXene demonstrated enhanced performance (η ≈ 140 mV, Tafel slope ≈ 134 mV/dec), which was further surpassed by the high-entropy (multilayered) M-(Ti1/4V1/4Nb1/4Ta1/4)2CTz MXene (η ≈ 97 mV, Tafel slope ≈ 115 mV/dec). Exfoliating the high-entropy MXene into few-layered F- (Ti1/4V1/4Nb1/4Ta1/4)2CTz (F-Mxene) nanosheets yielded a tremendous enhancement, achieving an exceptional overpotential of 67 mV and a Tafel slope of 69 mV/dec. Alongside this superior activity, the high-entropy F-MXenes demonstrated tremendous electrochemical stability under prolonged operation, maintaining their performance for more than 55 h of continuous use. This combination of record-low overpotential, favorable kinetics, and robust durability establishes these compositionally complex, few-layered MXenes as a promising next-generation catalyst platform, paving the way for their application in efficient and sustainable hydrogen production systems.
Biomass valorization represents a critical frontier in green chemistry and energy chemistry, where the essence of transformation lies in the selective cleavage and reconstruction of key chemical bonds. Electrocatalysis, characterized by mild operating conditions and an environmentally benign nature, offers a highly promising and sustainable pathway for upgrading waste biomass into value-added products. From the perspective of chemical bonds, this review systematically summarizes the latest research progress in electrocatalytic biomass valorization. First, the underlying microscopic electron/proton transfer mechanisms involved in electrocatalytic oxidation and reduction are discussed. Next, the cleavage and reconstruction of key chemical bonds, including C–H, C–O, C–C, C–N, and C–S bonds, are highlighted, with an in-depth analysis of substrate activation mechanisms, reaction pathways, and corresponding catalyst design strategies. Additionally, this review analyzes the regulatory mechanisms by which the interfacial microenvironment governs the conversion selectivity of different chemical bonds. Finally, perspectives on the core challenges currently facing this field are provided, including the insufficient elucidation of dynamic reaction mechanisms, the limited development of industrial-grade and stable catalysts, and the slow progress in scaling up electrolysis devices and processes. This review aims to provide theoretical guidance and new insights for the rational design of highly selective electrocatalysts for biomass valorization. This review summarizes key advances in electrocatalytic biomass valorization from the perspective of chemical bonds, focusing on the selective cleavage and reconstruction of C–H, C–O, C–C, C–N, and C–S bonds, substrate activation pathways, and rational catalyst design, offering theoretical guidance for designing highly selective electrocatalysts for biomass upgrading.
Preferential oxidation of CO (CO-PROX) is essential for H2 purification in proton-exchange membrane fuel cells. Understanding the intrinsic electronic structural factors that influence catalytic performance is key to rational catalyst design. Using Pt single-atom catalysts supported on Fe2O3 and Fe3O4 as model systems, this work systematically investigates the relationship between structure and performance, focusing on the strength of selective orbital coupling and CO-PROX activity. On both supports, Pt single atoms are stabilized in an embedded form by substituting lattice Fe sites (Pt1@FeOx). Furthermore, CO and H2 are preferentially activated at Pt-lattice O bridge sites, while O2 activation occurs at Pt sites. Compared to the Pt1@Fe3O4 system, the Pt1@Fe2O3 system exhibits higher theoretical activity and selectivity, with energy barriers of 0.28 eV for CO oxidation and 0.87 eV for H2 oxidation. The enhanced performance of Pt1@Fe2O3 stems from its higher lattice O redox activity and an optimal selective orbital coupling strength, measured by the descriptor Σ|Δε| (the absolute value sum of band‑center shifts for the dominant interacting orbitals). This creates a clear energetic preference for activating CO over H2. This study establishes a semiquantitative structure–activity relationship linking electronic structure, adsorption strength, and catalytic performance, providing concrete theoretical guidance for experimental design of high-performance CO-PROX catalysts.
Single-component ZnIn2S4 (ZIS) exhibits rapid charge recombination, resulting in low photocatalytic efficiency. To address this issue, the construction of an S-scheme heterojunction is a feasible strategy. Herein, a ZIS/dopamine (PDA) S-scheme heterojunction photocatalyst was successfully fabricated by depositing PDA onto the surface of ZIS nanoflowers. The optimized ZIS/PDA composite shows a significantly improved H2 production rate compared to pure ZIS and PDA. In situ irradiated X-ray photoelectron spectroscopy provides steady-state spectral evidence of S-scheme electron transfer from ZIS to PDA upon photoexcitation. Furthermore, transient spectral evidence for the ZIS/PDA S-scheme heterojunction is revealed via femtosecond transient absorption spectroscopy. Analysis of the charge dynamics in the ZIS component identifies an additional ultrafast lifetime component in the ZIS/PDA composites. This newly identified component is primarily attributable to the S-scheme interfacial electron transfer channel. The S-scheme electron transfer process gradually accelerates with increasing PDA concentration, ultimately reaching an optimal interfacial electron transfer lifetime of 0.9 ps. This ultrafast electron transfer dynamics facilitates the participation of photogenerated charge carriers in photocatalytic H2 evolution. Overall, this study provides new insights into the transient spectral analysis of S-scheme photocatalysts.
The practical application of aqueous zinc-ion batteries is critically hindered by the instability of the zinc metal anode, which suffers from uncontrollable dendrite growth and detrimental side reactions. Conventional electrolyte additives often focus solely on homogenizing the zinc-ion flux, while neglecting the pivotal role of crystallographic regulation. Herein, we propose a fundamental strategy to manipulate zinc deposition behavior through selective molecular adsorption. We introduce 2-aminoethylphosphonic acid (AEP) as a novel electrolyte additive that preferentially adsorbs onto the (100) and (101) crystal planes of zinc, as confirmed by experimental evidence from electric double-layer capacitance measurements, and theoretical DFT calculations, which reveal a lower adsorption energy on the (002) facet. Consequently, the AEP-modified electrolyte enables a densely packed zinc morphology and a significantly optimized interface, which collectively contribute to markedly enhanced electrode kinetics and cycling stability. The improved negative electrolyte enables the zinc-iodine flow battery (ZIFB) to operate for 600 h (1500 cycles) with a high energy efficiency (> 83
Atomic force microscopy (AFM) has become an essential tool for probing electrode surfaces, nanoscale reactions, and material properties in electrochemical research. By exploiting tip–sample interactions, AFM enables ultrahigh-resolution imaging of surface topography and enables the in situ monitoring of structural and morphological evolution during electrochemical processes. This review strategically explores two pivotal domains—energy-related electrocatalysis and batteries—to elucidate the microscopic mechanisms behind phenomena, such as lithium deposition/stripping, solid–electrolyte interphase formation, and key reactions, including carbon dioxide electroreduction and hydrogen evolution reduction. Within these contexts, AFM-based force spectroscopy (e.g., force–displacement curves) provides insights into the mechanical properties of electrodes and interfacial layers, offering critical data for material design and optimization. Furthermore, electrical modes, including Kelvin probe force microscopy and conductive AFM, enable the nanoscale characterization of local conductivity and surface potential. Complementing these, piezoresponse force microscopy probes electromechanical coupling and ferroelectric domain dynamics, revealing how local polarization and strain govern ion transport and catalytic activity. Together, these techniques advance electrochemical studies from macroscopic averaging toward in situ, spatially resolved, and heterogeneous mechanistic analysis. The fundamental insights gained from this review deepen our understanding of electrochemical processes and offer a promising avenue for advancing related fields, such as supercapacitors, fuel cells, and photoelectrochemical systems. This review systematically examines various AFM operating modes to highlight recent advances in the nanoscale characterization of electrode materials for diverse energy-related electrocatalysis and battery systems. Furthermore, it critically discusses current limitations, emerging challenges, and future perspectives.
A critical challenge in solar-driven water splitting is developing efficient photocatalysts for the oxygen evolution reaction without relying on metal cocatalysts. Herein, we address this challenge by employing amide linkage engineering in donor–acceptor covalent organic polymers (COPs). Two such polymers, COP-M and COP-I, were synthesized via straightforward sol–gel condensation of acyl chlorides (donor) and melamine (acceptor). The inherent donor–acceptor structure of these COPs imparts an appropriate bandgap ( 2.9 eV), facilitating effective intramolecular charge separation. Remarkably, these metal-free COPs exhibit intrinsic visible-light-driven oxygen evolution activity without any metal cocatalysts. Their performance can be enhanced approximately fivefold by introducing Co2+, with COP-M achieving an optimal O2 evolution rate of 106 μmol/h. Both experimental and theoretical analyses suggest that the polar amide bond enhances surface hydrophilicity and modulates the thermodynamic barrier for initial water activation. Additionally, enhanced charge separation and transfer kinetics within the symmetrical donor–acceptor architecture of COP-M underscore its enhanced performance. This study emphasizes the collaborative role of amide linkages and donor–acceptor motifs in designing metal-free polymer photocatalysts, offering a strategy for artificial photosynthesis.
The high cost and scarcity of noble metal anode catalysts significantly hinder the commercialization of proton exchange membrane (PEM) water electrolyzers. These limitations have inspired the development of non-noble metal oxygen evolution reaction (OER) catalysts with high activity and stability for large-scale green hydrogen production. Herein, we report the synthesis of a Ce-modulated cobalt (II, III) oxide (CeCo3O4) OER catalyst via metal–organic framework-assisted electrodeposition and low-temperature annealing. This catalyst enables the construction of three-dimensional (3D) cubic architectures on carbon cloth (CC) via controllable defect chemistry, where Ce incorporation effectively modulates the electronic structure of Co sites by regulating the Co3+/Co2+ ratio and oxygen vacancies, thereby stabilizing the catalyst, even under acidic OER conditions. The resulting optimized 3D-CeCo3O4//CC catalyst delivers an overpotential of 202 mV at a current density of 10 mA/cm2 in 0.5 mol/L sulfuric acid and exhibits durable operation with minimal potential drift over 100 h. When implemented as the anode of a practical PEM electrolyzer featuring a Pt/C cathode (1 mg/cm2), the device delivers a current density of 100 mA/cm2 at 1.788 V, maintaining stable operation at 50 mA/cm2 for 15 h with a voltage fluctuation. This performance surpasses those of most reported non-noble metal OER catalysts, with an efficiency gap that remains relative to those of previous state-of-the-art noble metal-based systems. These results reveal that Ce-induced electronic modulation and oxygen vacancy engineering synergistically enhance the acidic OER activity and stability of Co3O4, offering a viable, scalable strategy for developing non-noble metal OER catalysts for practical PEM water electrolyzers.
Chiral assembly endows perovskite materials with well-defined structural chirality and optical anisotropy, creating unique opportunities for multidimensional modulation in optoelectronic applications. Recent advances have demonstrated effective amplification of chiral signals, band structure engineering, and enhanced spin–orbit coupling through diverse strategies, including template-guided assembly, ligand-induced assembly, and several emerging approaches. This review highlights the latest progress in chiral perovskites for circularly polarized light-emitting devices, polarization-sensitive photodetectors, polarization imaging, optical communication and encryption, and spintronic and quantum information applications. Particular attention is devoted to the mechanistic correlations between assembly strategies and key performance parameters of chiral perovskites, such as dissymmetry factors, photoluminescence quantum yields, spin polarization degrees, and device stability. Representative studies are analyzed to elucidate the interplay between material architecture and device functionality. Despite remarkable progress, challenges remain, including limited stability, chirality retention, interface engineering, and scalable fabrication. Looking forward, the integration of multiple assembly strategies with multiscale theoretical modeling and machine learning-assisted design is anticipated to accelerate the translation of chiral perovskites from laboratory demonstrations to real-world applications in advanced optoelectronic devices, secure communication systems, and quantum information technologies.
Harnessing solar energy through photocatalysis offers a promising pathway for sustainable energy conversion and environmental remediation. Central to this progress is the development of efficient photocatalysts capable of activating inert N2 molecules under mild conditions. Recently, dual-atom catalysts (DACs) have emerged as a transformative class of materials that bridge the gap between single-atom and nanoparticle catalysts by providing synergistic bimetallic active sites with maximized atomic utilization. This review concisely summarizes recent advances in the coordination microenvironment, structural design, and catalytic mechanisms of transition metal-based dual-atom catalysts (TM-DACs) for photocatalytic N2 conversion. Particular emphasis is placed on how electronic coupling, metal–metal interactions, and coordination configuration of TM-DACs govern charge transfer dynamics, adsorption behavior, and reaction kinetics during the N2 reduction process. Synthesis strategies, characterization techniques, and mechanistic pathways of TM-DACs are comprehensively discussed, highlighting their advantages over single-atom systems. Furthermore, emerging trends and challenges in developing noble metal-free, earth-abundant DACs for efficient NH3 production are outlined. This review aims to provide fundamental insights and design principles for constructing next-generation TM-DACs for highly efficient and sustainable photocatalytic applications. Schematic of the coordination microenvironment and dual-metal synergy in transition metal-based dual-atom catalysts (TM-DACs) for photocatalytic N2 fixation. Design strategies, active site interactions, charge transfer pathways, and reaction mechanisms are highlighted to guide the development of effective and sustainable photocatalysts for NH3 production.
Sluggish kinetics of water electrolysis is a major challenge in the practical dissociation of water to form gaseous H2 and O2. Electrocatalysts are required for enhancing the performance of the water splitting process. This study addresses this issue by examining the synthesis of ZnS quantum dots (QDs), a metal-organic framework containing Dy (Dy-MOF), and the composite of these species (ZnS@Dy-MOF), as well as their potential use as electrocatalysts for water splitting. ZnS QDs were integrated into the MOF during synthesis to achieve enhanced conductivity and stability, aiming to harness the synergetic effect in the resulting material. The properties of ZnS@Dy-MOF were exploited in practical use to address the urgent demand for effective water splitting catalysts. The morphological, structural, and compositional properties of the ZnS QDs, Dy-MOF, and ZnS@Dy-MOF were examined via various characterization techniques. The ZnS@Dy-MOF composite emerged as the optimal electrocatalyst for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with a low overpotential of 228 mV for the HER and 138 mV for the OER at a current density of 10 mA/cm2. The ZnS@Dy-MOF composite also had a relatively small onset potential of 1.47 V versus RHE with 50 h of electrochemical sustainability. The synergistic interaction between the ZnS QDs and Dy-MOF conferred remarkable catalytic efficiency and significant stability to the electrocatalyst. The foremost objective of this research is to study the extraordinary potential of Dy-MOF and its composites for applications involving water splitting.
