Sites For Water Splitting Research Articles

Creating Dual Active Sites in Ru-doped FeMn-MOF-74 for Efficient Overall Water Splitting.

The design of well-engineered bifunctional electrocatalysts is crucial for achieving durable and efficient performance in overall water splitting. In this study, Ru-doped FeMn-MOF-74 itself has Ru sites and generates FeMnOOH under catalytic conditions, forming dual active sites for overall water splitting. Density functional theory (DFT) calculations demonstrate that the Ru dopants exhibit optimized binding strength for H* and enhanced hydrogen evolution reaction (HER) performance. Moreover, the Mn sites within FeMnOOH lower the energy barrier for the rate-determining step (from O* to OOH*), serving as the active centre for oxygen evolution reaction (OER). The incorporation of Ru significantly improves the electron transfer properties of FeMn-MOF-74 and enhances its water adsorption capacity, synergistically boosting its bifunctional activity. This strategy of designing dual active sites provides new insights into the development of bifunctional metal-organic frameworks (MOFs) for efficient overall water splitting.

Designing Ru-B-Cr Moieties to Activate the Ru Site for Acidic Water Electrolysis under Industrial-Level Current Density.

Developing highly efficient non-iridium-based active sites for acidic water splitting is still a huge challenge. Herein, unique Ru-B-Cr moieties have been constructed in RuO2 nanofibers (NFs) to activate Ru sites for water electrolysis, which overcomes the bottleneck of RuO2-based catalysts usually possessing low activity for the hydrogen evolution reaction (HER) and poor stability for the oxygen evolution reaction (OER). The fabricated Cr, B-doped RuO2 NFs exhibit low overpotentials of 205 and 379 mV for acidic HER and OER at 1 A cm-2 with outstanding stability lasting 1000 and 188 h, respectively. The assembled acidic electrolyzer also possesses great hydrogen production efficiency and durability at a high current density. Experimental and theoretical explorations reveal that the formation of Ru-B-Cr moieties effectively optimizes the atomic configurations and modulates the adsorption/desorption free energy of reaction intermediates to achieve exceptional HER and OER performance.

Correlation between ligand-mediated silver species on TiO2 nanosheet with the photocatalytic hydrogen evolution activities.

Metal oxide photocatalysts loaded with metal species are extremely important in photocatalysis. The physicochemical states of metal species, as well as the interaction between metal species and support, determine the transfer of charge carriers between the heterointerface, which has a significant impact on photocatalytic activity. Here, we prepared anatase TiO2 nanosheets (TIO) modified with different Ag species, including single atoms, clusters, and nanoparticles, using a ligand-mediated method. The existence of different forms of Ag species on TIO was verified by high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) and high-resolution transmission electron microscope (HRTEM); Electron paramagnetic resonance (EPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirmed the changed electronic properties in heterointerface and charge carrier transfer channels caused by the Ag species in different existence states; X-ray absorption fine structure (XAFS) in depth differentiated the valence states, coordination environments, and charge densities of Ag species. It is intriguing that the photocatalytic hydrogen evolution activity exhibits a hump shape, which can be attributed to the changes in the physicochemical properties of silver species in different states. In addition, the combination of density functional theory (DFT) calculations and experimental results demonstrated that the Ag single atom acted as an active site for water splitting, while the Ag cluster tended to attract electrons and promoted charge separation efficiency. This work delves into the relationship between the microscopic changes of metal species anchored on the surface of photocatalysts and their photocatalytic performance, providing further insights into precise surface engineering and performance optimization by adjusting the metal presence state on the photocatalyst surface.

Constructing Dense CoRu-CoMoO4 Heterointerfaces with Electron Redistribution for Synergistically Boosted Alkaline Electrocatalytic Water Splitting.

Constructing metal alloys/metal oxides heterostructured electrocatalysts with abundant and strongly coupling interfaces is vital yet challenging for practical electrocatalytic water splitting. Herein, CoRu nanoalloys uniformly anchored on CoMoO4 nanosheet heterostructured electrocatalyst (CoRu-CoMoO4/NF) are synthesized via a self-templated strategy by simply annealing of Ru-etched CoMoO4/NF precursor in a reduction atmosphere. The dense and robustly coupled interface not only provides abundant active sites for water splitting but also strengthens the charge transfer efficiency. Furthermore, the theoretical calculations unveil that the strong electronic interaction at CoRu-CoMoO4 interface can induce an interfacial electron redistribution and reduce the energetic barriers for the hydrogen and oxygen intermediates, thereby accelerating the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics. The resultant catalyst only requires the overpotentials of 49mV for HER and 209mV for OER at 10mAcm-2. Moreover, the constructed CoRu-CoMoO4||CoRu-CoMoO4 two-electrode cell achieves a cell voltage of 1.54V at 10mAcm-2, outperforming the benchmark Pt/C||IrO2. This work explores an avenue for the rational design of heterostructured electrocatalysts with abundant interfaces for practical water-splitting electrocatalysis.

Electrospun Co-MoC Nanoparticles Embedded in Carbon Nanofibers for Highly Efficient pH-Universal Hydrogen Evolution Reaction and Alkaline Overall Water Splitting.

The construction of highly efficient and self-supported electrocatalysts with abundant active sites for pH-universal hydrogen evolution reaction (HER) and alkaline water splitting is significantly challenging. Herein, Co and MoC nanoparticles embedded in nitrogen-doped carbon nanofibers (Co-MoC/NCNFs) which display a bamboo-like morphology are prepared by electrospinning followed by the carbonization method. The electrospun MoC possesses an ultrasmall size (≈5nm) which can provide more active sites during electrocatalysis, while the introduction of Co greatly optimizes the electronic structure of MoC. Both endow the Co-MoC/NCNFs with superior HER performances over a wide pH range, with low overpotentials of 86, 116, and 145mV to achieve a current density of 10mAcm-2 in alkaline, acidic, and neutral media, respectively. Additionally, the catalyst exhibits remarkable alkaline oxygen evolution reaction (OER) activity with an overpotential of 254mV to reach 10mAcm-2. Density functional theory calculations confirm that electron transfer from Co to MoC regulates the adsorption free energy for hydrogen, thereby promoting HER. Moreover, an electrolyzer assembled with Co-MoC/NCNFs requires only a cell voltage of 1.59V at 10mAcm-2 in 1m KOH. This work opens new pathways for the design of high-efficiency electrocatalysts for energy conversion applications.

Construction of COF/COF Organic S-Scheme Heterostructure for Enhanced Overall Water Splitting.

Covalent organic frameworks (COFs) as a new type of photocatalysts have shown unique advantages in visible-light-driven hydrogen evolution, while the reported overall water-splitting systems are still very rare among various COF-based photocatalysts. Herein, two COFs are integrated to construct a type of organic S-scheme heterojunction for improved overall water splitting. In this system, TpBpy-COF and COF-316 serve as H2- and O2-evolving components, respectively, which are combined through π-π interaction between conjugated aromatic rings. By introducing ultra-small Pt nanoparticles (NPs) into the pores of the TpBpy-COF nanosheets (NS), the resultant COF-316/Pt@TpBpy-COF NS heterostructure achieves extremely high H2 and O2 evolution rates of 220.4 and 110.2µmolg-1h-1, respectively, under visible light irradiation (λ ≥ 420nm). The results of transient absorption spectra (TAS) and photoelectronic measurements indicate that the organic heterojunction interface notably facilitates the separation and transfer of photogenerated electron-hole pairs. Further, theoretical calculations and in situ experiments confirm the spontaneous formation of the COF/COF heterojunction interface and the active sites for overall water splitting.

Ultrafine Rhodium-Chromium Mixed-Oxide Cocatalyst with Facet-Selective Loading for Excellent Photocatalytic Water Splitting.

The development of water-splitting photocatalysts capable of generating green hydrogen (H2) from water and sunlight is crucial for achieving carbon neutrality. Further enhancement of the photocatalytic water-splitting activity is essential to realizing this objective. Photocatalysts with specific exposed crystal facets can facilitate efficient charge separation of electrons/holes, thereby achieving high activity for water splitting. However, there have been no reports of ultrafine (∼1 nm) cocatalysts being loaded onto specific crystal facets of photocatalysts, despite cocatalysts being the actual reaction sites for water splitting. This study establishes a novel method for achieving facet-selective loading of ultrafine H2-evolution cocatalysts onto the {100} facets, which are the H2-evolution facets, of a strontium titanate photocatalyst. The resulting photocatalyst exhibits the highest apparent quantum yield achieved to date for strontium titanate. This research holds the potential to further improve various types of advanced photocatalysts and is expected to accelerate the transition to carbon neutrality.

Advanced design of metal single-atom (Pt, Mn, Fe or Cu) loaded S-Ni(OH)2 nanosheets array catalysts to achieve high-performance overall water splitting

Designing catalysts at atomic level fine-tune the electronic structure of surface-active site for efficient water splitting, is a highly desirable approach but also poses significant challenges. This study focuses on the synthesis of a series of electronically tunable metal single-atom (M−SAs) catalysts: M9@S-Ni(OH)2 (M=Pt, Mn, Fe or Cu). Experimental results reveal that introduction of trace S-heteroatoms and metal atoms into Ni(OH)2 lattice can effectively modulate the electronic structure of M9@S-Ni(OH)2 through modulation of p-d and d-d orbital hybridization, resulting in exceptional performance in water electrolysis. Among M9@S-Ni(OH)2, Pt9@S-Ni(OH)2 and Fe9@S-Ni(OH)2 exhibit excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance, respectively, the overpotential requiring only 7 mV and 269 mV, respectively, at current density of 10 mA cm−2. (−) Pt9@S-Ni(OH)2||Fe9@S-Ni(OH)2 (+) presents a high current density of 531.07 mA cm−2 at cell-voltage of 1.80 V in overall-water splitting (OWS), which is 14.07 times higher than that of the commercial (−) Pt/C||IrO2 (+) (37.86 mA cm−2) system. This work achieves the development of cost-effective and stable electrocatalysts, offering a solution for large-scale and sustainable water-hydrogen conversion.

Atomically dispersed ruthenium in transition metal double layered hydroxide as a bifunctional catalyst for overall water splitting

Efficient and sustainable energy conversion depends on the rational design of single-atom catalysts. The control of the active sites at the atomic level is vital for electrocatalytic materials in alkaline and acidic electrolytes. Moreover, fabrication of effective catalysts with a well-defined surface structure results in an in-depth understanding of the catalytic mechanism. Herein, a single atom ruthenium dispersed in nickel-cobalt layered hydroxide (Ru-NiCo LDH) is reported. Through the precise controlling of the atomic dispersion and local coordination environment, Ru-NiCo LDH//Ru-NiCo LDH provides an ultra-low overpotential of 1.45 mV at 10 mA cm−2 for the overall water splitting, which surpasses that of the state-of-the-art Pt/C/RuO2 redox couple. Density functional theory calculations show that Ru-NiCo LDH optimizes hydrogen evolution intermediate adsorption energies and promotes O-O coupling at a Ru-O active site for oxygen evolution, while Ni serves as the water dissociation site for effective water splitting. As a potential model, Ru-NiCo LDH shows enhanced water splitting performance with potential for the development of promising water-alkaline catalysts.

Efficient Holes Abstraction by Precisely Decorating Ruthenium Single Atoms and RuOx Clusters on ZnIn2S4 for Photocatalytic Pure Water Splitting.

Developing efficient photocatalysts for two-electron water splitting with simultaneous H2O2 and H2 generation shows great promise for practical application. Currently, the efficiency of two-electron water splitting is still restricted by the low utilization of photogenerated charges, especially holes, of which the transfer rate is much slower than that of electrons. Herein, Ru single atoms and RuOx clusters are co-decorated on ZnIn2S4 (RuOx/Ru-ZIS) to employ as multifunctional sites for efficient photocatalytic pure water splitting. Doping of Ru single atoms in the ZIS basal plane enhances holes abstraction from bulk ZIS by regulating the electronic structure, and RuOx clusters offer a strong interfacial electric field to remarkably promote the out-of-plane migration of holes from ZIS. Moreover, Ru single atoms and RuOx clusters also serve as active sites for boosting surface water oxidation. As a result, an excellent H2 and H2O2 evolution rates of 581.9 µmolg-1h-1 and 464.4 µmolg-1h-1 is achieved over RuOx/Ru-ZIS under visible light irradiation, respectively, with an apparent quantum efficiency (AQE) of 4.36% at 400nm. This work paves a new way to increase charge utilization by manipulating photocatalyst using single atom and clusters.

2D MXene-derived 3D TiO2-NiCoPx hierarchical heterostructures for efficient water splitting

Achieving efficient electrocatalytic activity in two-dimensional (2D) MXene for advanced water splitting remains a significant challenge. In this work, 2D MXene was derived into sea urchin-like TiO2 and used to load porous bimetallic phosphide (NiCoPx) nanorods to achieve three-dimensional (3D) TiO2-NiCoPx hierarchical heterostructures. The hierarchical heterostructures synthesized through hydrothermal and phosphating processes enable rich heterogeneous interfaces and fully exposed active sites, thereby facilitating efficient charge transfer and accelerating mass transfer rates. As a result, the TiO2-NiCoPx heterostructures inherit the low overpotential (311 mV at 10 mA cm−2) and long-term stability (current density retention of 94.1 % after 12 h) towards oxygen evolution reaction (OER). Importantly, the assembled TiO2-NiCoPx || Pt/C cell also exhibits remarkable water splitting performance. This contribution delivers a desirable opportunity for constructing efficient 2D MXene-based electrocatalysts with abundant active sites for water splitting.

Exploring the Deprotonation Process during Incorporation of a Ligand Water Molecule at the Dangling Mn Site in Photosystem II.

The Mn4CaO5 cluster, featuring four ligand water molecules (W1 to W4), serves as the water-splitting site in photosystem II (PSII). X-ray free electron laser (XFEL) structures exhibit an additional oxygen site (O6) adjacent to the O5 site in the fourth lowest oxidation state, S3, forming Mn4CaO6. Here, we investigate the mechanism of the second water ligand molecule at the dangling Mn (W2) as a potential incorporating species, using a quantum mechanical/molecular mechanical (QM/MM) approach. Previous QM/MM calculations demonstrated that W1 releases two protons through a low-barrier H-bond toward D1-Asp61 and subsequently releases an electron during the S2 to S3 transition, resulting in O•- at W1 and protonated D1-Asp61. During the process of Mn4CaO6 formation, O•-, rather than H2O or OH-, best reproduced the O5···O6 distance. Although the catalytic cluster with O•- at O6 is more stable than that with O•- at W1 in S3, it does not occur spontaneously due to the significantly uphill deprotonation process. Assuming O•- at W2 incorporates into the O6 site, an exergonic conversion from Mn1(III)Mn2(IV)Mn3(IV)Mn4(IV) (equivalent to the open-cubane S2 valence state) to Mn1(IV)Mn2(IV)Mn3(IV)Mn4(III) (equivalent to the closed-cubane S2 valence state) occurs. These findings provide energetic insights into the deprotonation and structural conversion events required for the Mn4CaO6 formation.

Neighboring V atom as a catalytic switch: Reversing the active site for exceptional water splitting

Due to the different reaction substrates are involved in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), bifunctional catalysts with diverse active sites are crucial for electrochemical water splitting. However, it is extremely difficult to design sites that are catalytically active for both H- and O-containing intermediates. Herein, neighboring V site on poor-active FeN4 site can reverse the active center of HER from Fe sites to N sites and simultaneously boost the activity of Fe sites for OER. Water splitting on FeV-NC requires only 1.57 V to achieve 10 mA cm−2 along with an overpotential of 233.2 mV for OER and 88.8 mV for HER. Theoretical calculations reveal that the presence of neighboring V site shifts the pz centres of the bridging N atoms positively and intensifies the electronic spin and 3d orbital of Fe atoms, which optimizes the interaction of the H/O-containing reactant/intermediate on N and Fe sites.

Constructing heterojunctions of CoAl2O4 and Ni3S2 anchored on carbon cloth to acquire multiple active sites for efficient overall water splitting

Constructing heterojunction interface is an efficient strategy to accelerate the catalytic activity for electrochemical reaction. In this work, a novel composite heterojunction electrocatalyst (CAO/NiS400/CC), deriving from the combination of CoAl2O4 (CAO) and Ni3S2 anchored on carbon cloth (CC) was prepared, through hydrothermal process followed by electrodeposition. After successful synthesis, CoAl2O4 particles were intricately embedded in Ni3S2 and formed an active heterostructure, exhibited outstanding catalytic capacity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) and improved the efficiencies of overall water splitting. As expected, the composite heterojunction electrocatalyst demonstrated excellent catalytic performances with lower overpotential of 163.2 mV at 100 mA·cm−2 and Tafel slope of 20.4 mV·dec-1for HER and 400 mV at 100 mA·cm−2 and Tafel slope of 51.1 mV·dec-1 for OER, respectively, accompanied by long-term structural stability after 40 h and 3000 Cyclic Voltammetry (CV) cycles. Moreover, Density functional theory (DFT) calculation illustrated that the robust electrocatalytic performance was attributed to the simultaneous presence of multiple catalytic active sites surrounding the heterojunction interface. Furthermore, CAO/NiS400/CC electrocatalyst facilitated the overall water splitting reaction under a cell voltage of only 1.48 V with dual catalytic capabilities for HER and OER. The combined action of active catalytic sites within both CAO and Ni3S2 around the interface contributed the optimal electrocatalytic performance, making the CAO/NiS400/CC as a promising alternative to electrocatalysts for water splitting.

Advanced electrocatalysts with unusual active sites for electrochemical water splitting

AbstractElectrochemical water splitting represents a promising technology for green hydrogen production. To design advanced electrocatalysts, it is crucial to identify their active sites and interpret the relationship between their structures and performance. Materials extensively studied as electrocatalysts include noble‐metal‐based (e.g., Ru, Ir, and Pt) and non‐noble‐metal‐based (e.g., 3d transition metals) compounds. Recently, advancements in characterization techniques and theoretical calculations have revealed novel and unusual active sites. The present review highlights the latest achievements in the discovery and identification of various unconventional active sites for electrochemical water splitting, with a focus on state‐of‐the‐art strategies for determining true active sites and establishing structure–activity relationships. Furthermore, we discuss the remaining challenges and future perspectives for the development of next‐generation electrocatalysts with unusual active sites. By presenting a fresh perspective on the unconventional reaction sites involved in electrochemical water splitting, this review aims to provide valuable guidance for the future study of electrocatalysts in industrial applications.image

Ni3S4/FeNi2S4 heterostructure-embedded metal-organic framework-derived nanosheets interconnected by carbon nanotubes for boosting oxygen evolution reaction

The efficiency of electrolytic water splitting is hampered by the slow kinetics of the oxygen evolution reaction (OER). Addressing this challenge, we present a novel catalyst with rich Ni3S4/FeNi2S4 heterostructures anchored metal-organic framework-derived nanosheets interconnected by carbon nanotubes (NiFe–S@CNT). The NiFe–S@CNT electrocatalyst shows an ultralow overpotential of 246 mV at a current density of 10 mA/cm2 (η10), surpassing the benchmark RuO2 (η10 = 291 mV) as well as many reported sulfide electrocatalysts. The strong heterointerface interaction between Ni3S4 and FeNi2S4 induce synergistic effects, modifying the electronic structure of active sites and generating a large number of lattice defects. Additionally, the carbon nanotubes skeleton facilitates efficient electron transfer and enhances electrical conductivity during the catalytic process. Moreover, the metal-organic framework derivative inherits a porous structure, aiding in electrolyte penetration and efficient bubble release. This study provides a facile and scalable strategy to develop nonprecious transition-metal-based OER catalysts with abundant heterointerfaces and active sites for efficient water splitting.

Ternary-role of NiCo-MOFs for boosting the photocatalytic H2-evolution and long term stability of CdS

CdS is a promising candidate for visible-light-driven photocatalytic H2-evolution, but its practical application is still limited by self-photo-corrosion and noble co-catalysts needing. Herein, CdS/NiCo-MOFs (CM) heterojunction was synthesized by an in-situ hydrothermal method, where NiCo-MOFs (BMOFs) acted as platform to inhibit the aggregation of CdS nanoparticles. Furthermore, BMOFs provided dual-reaction sites to improve the photocatalytic H2-evolution speed and suppress the photo-corrosion of CdS by taking its Ni-linker as catalytic active sites for water splitting and Co-linker as hole trapping sites to suppress the self-oxidation between S2− and holes. Therefore, the optimal CM-20% exhibited a remarkable photocatalytic H2-evolution rate of 1.810 mmol g−1 h−1 under sunlight irradiation, which is 4.55 times higher than that of CdS. Moreover, CM-20% maintained this high photocatalytic H2-evolution rate for 100 h reaction, which for CdS is just 50 h. This research provides insight into designing high-efficiency and photo-stable sulfide-based photocatalyst systems for H2-evolution.

Non-covalent interaction of atomically dispersed dual-site catalysts featuring Co and Ni nascent pair sites for efficient electrocatalytic overall water splitting

The scarcity of highly effective and economical catalysts is a major impediment to the widespread adoption of electrochemical water splitting for the generation of hydrogen. MoS2, a low-cost candidate, suffers from inefficient catalytic activity. Nonetheless, a captivating strategy has emerged, which involves the engineering of heteroatom doping to enhance electrochemical proficiency. This investigation demonstrates a successful implementation of the strategy by combining ultrathin MoS2 nanosheets with Co and Ni dual single multi-atoms (DSMAs) grown directly on 2D N-doped carbon nanosheets (CoNi-MoS2/NCNs) for the purpose of improving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). With the aid of a dual-atom doped bifunctional electrocatalyst, effective water splitting has been achieved across a broad pH range in electrolytes. The double doping of Co and Ni strengthens their interactions, thereby altering the electromagnetic composition of the host MoS2 and ultimately leading to improved electrocatalytic activity. Additionally, the synergistic effect between NCNs and MoS2 nanosheets provided efficient electron transport channels for ions and an ample surface area with open voids for ion diffusion. Consequently, the CoNi-MoS2/NCNs catalysts demonstrated exceptional stability and activity, producing low degree overpotentials of 180.5, 124.9, and 196.4 mV for HER and 200, 203, and 207 mV for OER in neutral, alkaline, and acidic mediums, respectively, while also exhibiting outstanding overall water-splitting performance, durability, and stability when used as an electrolyzer at universal pH.

Photocatalytic Water Splitting Driven by Surface Plasmon Resonance

AbstractSurface plasmon resonance (SPR) in metals results in unique optical properties and photoelectric functions, which are helpful for light harvesting in photocatalysis. Additionally, the plasmon‐associated charge transfer process gives a complementary platform to understand the charge dynamics at a fundamental level. This Review focused on the recent developments of water splitting by plasmonic metals/semiconductor photocatalysts. Firstly, the basic characteristics of SPR and the plasmon‐enhanced photocatalysis mechanisms including plasmon resonance energy transfer and interfacial charge transfer are introduced, highlighting the recent understanding of the plasmonic electron‐hole separation, distribution, and the reaction sites for water splitting. Then, advances in the strategies to improve the quantum efficiency of plasmon‐induced water splitting are summarized by considering modulation in metals, interface contacts, and bulk properties of semiconductors. Finally, we discuss future prospects in the development of high‐efficiency plasmonic metal/semiconductor photocatalysts for water splitting.

Ni-Activated and Ni-P-Activated Porous Titanium Carbide Ceramic Electrodes as Efficient Electrocatalysts for Overall Water Splitting.

Developing electrocatalysts based on transition-metal carbides that can be utilized for commercial water splitting is a challenging endeavor. To address this challenge, we employed a novel approach that merged phase-inversion tape-casting and sintering, subsequently implementing a simple and efficient electrodeposition process, to synthesize Ni-activated and Ni-P-activated titanium carbide (Ni/TiC, Ni-P/TiC) ceramic electrodes as water splitting catalytic cathodes and anodes. These self-supported Ni/TiC and Ni-P/TiC electrodes are binder-free with abundant finger-like pores, which contribute to the formation of highly conductive skeleton and more exposed active sites for direct water splitting. These catalysts exhibit outstanding performance, superior to many reported bifunctional nickel-based catalysts supported on other substrates. Moreover, the exceptional electrocatalytic performance of the Ni/TiC and Ni-P/TiC catalysts is attributed to the synergistic effect between Ni oxides (phosphides) and TiC, as revealed by density functional theory (DFT) calculations. This self-template strategy paves the way for fabricating industrially applicable electrodes to generate hydrogen and oxygen through water splitting.