Surface Reconstruction Process Research Articles

Effect of Halide Anions on Electrochemical CO2 Reduction in Non-Aqueous Choline Solutions using Ag and Au Electrodes.

In this study, the effect of halide anions on the selectivity of the CO2 reduction reaction to CO was investigated in choline-based ethylene glycol solutions containing different halides (ChCl : EG, ChBr : EG, ChI : EG). The CO2RR was studied using silver (Ag) and gold (Au) electrodes in a compact H-cell. Our findings reveal that chloride effectively suppresses the hydrogen evolution reaction and enhances the selectivity of carbon monoxide production on both Ag and Au electrodes, with relatively high selectivity values of 84 % and 62 %, respectively. Additionally, the effect of varying ethylene glycol content in the choline chloride-containing electrolyte (ChCl : EG 1 : X, X=2, 3, 4) was investigated to improve the current density during CO2RR on the Ag electrode. We observed that a mole ratio of 1 : 4 exhibited the highest current density with a comparable faradaic efficiency toward CO. Notably, an evident surface reconstruction process took place on the Ag surface in the presence of Cl- ions, whereas on Au, this phenomenon was less pronounced. Overall, this study provides new insights into anion-induced surface restructuring of Ag and Au electrodes during CO2RR, and its consequences on the reduction performance on such surfaces in non-aqueous electrolytes.

Cation-Triggered Growth of Nanowires for Enhanced Oxygen Evolution Reaction.

The oxygen evolution reaction (OER), which occurs in a variety of energy-related devices, necessitates optimization of the reaction pathways for efficient and scalable deployment. Nevertheless, fully harnessing the advanced structure of synthetic electrocatalysts remains a significant challenge due to the inevitable surface reconstruction process during OER. Here we present an efficient and flexible method to control the surface reconstruction process by engineering an electrolyte containing trace Co2+ cation. This controllable reconstruction process enhances fast charge transfer, facilitates electroactive species transport, and exposes the inner active site, significantly improving the OER kinetics. An impressive 60% increase in current density at an applied potential of 2.2 V (vs RHE) confirms its remarkable contribution to the performance. The identification of cation-triggered reconstruction for the formation of a well-defined surface provides a novel insight into understanding electrolyte engineering and offers a viable pathway to address activity and stable concerns in electrocatalysts.

High-efficiency oxygen evolution reaction: Effect of phosphorus doped on the surface reconstruction of high-entropy spinel oxides

High entropy oxides (HEOs) are often used for the oxygen evolution reaction (OER) due to their tunable electronic structure, variable composition and structural stability. However, the catalytic activity of conventional HEOs is limited due to their high crystallinity, resulting in a low number of active sites on the surface. Anion doping, on the other hand, is a method that can effectively increase OER activity. In this study, a series of P-doped HEOs were synthesized and the effect of P doped on HEOs was investigated. It was found that P doped increased the metal (Co, Ni, Mn)-oxygen covalency in HEOs and generated a large number of oxygen vacancies. The electrochemical properties of HEOs with different P doped levels were also compared, and HEO-P-1 showed the best catalytic performance, reaching a current density of 10 mA cm−2 at an overpotential of only 254 mV. Then, the surface reconstruction process of HEO-P-1 was also investigated and it was found that the (oxygen) hydroxides of Co-Ni-Mn play a real catalytic role. Finally, the OER mechanism catalyzed by HEO-P-1 was investigated. This work provides a new idea for effective doping of anions in HEOs for efficient OER catalysis.

Enabling surface reconstruction through a heterostructured Ni3S4@NiCo2O4/NF towards efficient ammonia oxidation reaction

With ammonia playing a more and more vital role in serving as a renewable hydrogen carrier, it is critical to develop economical and efficient electrocatalysts for the ammonia oxidation reaction (AOR) in which hydrogen is released. In this work, a heterostructured electrocatalyst, Ni3S4@NiCo2O4/NF, was synthesized using the hydrothermal method for the purpose of improving AOR efficiency. The obtained nano catalyst exhibited an excellent AOR activity (10 mA·cm−2 at 0.58 V vs. Hg/HgO) and stability (37.2 h at 100 mA·cm−2). XRD and XPS characterizations indicated that the bulk catalyst remained unchanged yet with surface metallic Ni oxidized. In situ Raman spectroscopy analysis further revealed that the heterostructured catalyst underwent an obvious surface reconstruction process (Ni(OH)2 → β-NiOOH → γ-NiOOH) which accordingly lowered the potential required for reconstruction and optimized the energy barrier for the AOR. DFT calculations showed that the heterostructured catalyst not only favors the acceleration of the reconstruction process due to electronic interactions, but also reduces the energy barrier in *NHNH2 generation step, thus enhancing the performance of AOR, which is superior to the other two catalysts. The product gas analysis showed that the developed catalyst maintained an excellent Faraday efficiency of 95% and a continued activity. In summary, this work opened a potential new pathway for the design of heterostructured electrocatalysts for H2 production through AOR.

WO3-x as an activation medium to prompt overall water splitting of NiFe-based electrocatalyst

The efficient oxygen evolution reaction (OER) is crucial for various electrochemical processes, especially for overall water splitting (OWS). In this study, we focus on the utilization of WO3-x as an activation medium to enhance the OER performance of NiFe-based electrocatalysts. Firstly, we synthesize WO3-x nanowires supported on nickel foam (NF) and then incorporate NiFe on WO3-x nanowires by a simple hydrothermal method. The WO3-x self-supported NiFe (Oxy)hydroxide (denoted as NiFe-W-O/NF) shows a three-dimensional stereostructure composed of ultrathin nanosheets (∼ 4.0 nm). This unique structure provides a large open surface for fuller diffusion of the electrolyte while exposing more active sites. The electronic interaction of tri-centers of NiFeW accelerates the surface reconstruction process of γ-NiOOH and FeOOH, which are converted into the main active species in a short time. The electrochemical measurements confirm that the NiFe-W-O/NF has low OER overpotentials (233 mV at 10 mA cm−2, 298 mV at 100 mA cm−2) and excellent stability (100 h in total) in 1 M KOH electrolyte. In addition, the NiFe-W-O/NF || NiFe-W-O/NF battery also exhibits a low cell voltage (1.52 V at 10 mA cm−2) with a stable lifetime (50 h) under alkaline conditions. These results highlight the great potential of NiFe-W-O/NF for practical applications.

Ruthenium-Based Binary Alloy with Oxide Nanosheath for Highly Efficient and Stable Oxygen Evolution Reaction in Acidic Media.

Traditional noble metal oxide, such as RuO2, is considered a benchmark catalyst for acidic oxygen evolution reaction (OER). However, its practical application is limited due to sluggish activity and severe electrochemical corrosion. In this study, Ru-Fe nanoparticles loading on carbon felt (RuFe@CF) is synthesized via an ultrafast Joule heating method as an active and durable OER catalyst in acidic conditions. Remarkably low overpotentials of 188 and 269mV are achieved at 10 and 100mA cm-2, respectively, with a robust stability up to 620 h at 10mA cm-2. When used as an anode in a proton exchange membrane water electrolyzer, the catalyst shows more than 250 h of stability at a water-splitting current of 200mA cm-2. Experimental characterizations reveal the presence of a Ru-based oxide nanosheath on the surface of the catalyst during OER tests, suggesting a surface reconstruction process that enhances the intrinsic activity and inhibits continuous metal dissolution. Moreover, density functional theory calculations demonstrate that the introduction of Fe into the RuFe@CF catalyst reduces the energy barrier and boosts its activities. This work offers an effective and universal strategy for the development of highly efficient and stable catalysts for acidic water splitting.

From Atomic-Level Synthesis to Device-Scale Reactors: A Multiscale Approach to Water Electrolysis.

ConspectusThe development of an advanced energy conversion system for water electrolysis with high efficiency and durability is of great significance for a hydrogen-powered society. This progress relies on the fabrication of electrocatalysts with superior electrochemical performance. Despite decades of advancements in exploring high-performance noble and non-noble metal electrocatalysts, several challenges persist at both the micro- and macrolevels in the field of water electrolysis.At the microlevel, which encompasses electrocatalyst synthesis and characterization, design strategies for high-performance electrocatalysts have primarily focused on interface chemical engineering. However, comprehensive understanding and investigation of interface chemical engineering across various length scales, from micrometers to atomic scales, are still lacking. This deficiency hampers the rational design of catalysts with optimal performance. Under harsh reaction conditions, such as high bias potential and highly acidic or alkaline media, the surface of catalyst materials is susceptible to undergoing "reconstruction", deviating from what is observed through ex situ characterization techniques postsynthesis. Conventional ex situ characterization methods do not provide an accurate depiction of the catalyst's structural evolution during the electrocatalytic reaction, hindering the exploration of the catalytic mechanism.At the macrolevel, pertaining to catalysis-performance evaluation systems and devices, traditional laboratory settings employ a conventional three-electrode or two-electrode system to assess the catalytic performance of electrocatalysts. However, this approach does not accurately simulate hydrogen production under realistic industrial conditions, such as elevated temperatures (60-70 °C), high current densities exceeding 0.5 A cm-2, and flowing electrolytes. To address this limitation, it is crucial to develop testing equipment and methodologies that replicate the actual industrial conditions.In this Account, we propose a multiscale research framework for water electrolysis, spanning from microscale synthesis to macroscale scaled reactor design. Our approach focuses on the design and evaluation of high-performance HER/OER (hydrogen evolution reaction/oxygen evolution reaction) electrocatalysts, incorporating the following strategies: Leveraging principles of interface chemical engineering across various length scales (micrometers, nanometers, and atoms) enables the design of catalyst materials that enhance both activity and durability. This approach provides a comprehensive understanding of the intricate interplay between the catalyst structure and activity, implementing in situ/operando characterization techniques to monitor dynamic interfacial reactions and surface reconstruction processes. This facilitates a profound exploration of catalytic reaction mechanisms, offering insights into the catalyst's structural evolution during the electrocatalytic reaction. We construct a laboratory-scale membrane electrode assembly (MEA) electrochemical reactor capable of operating at high current densities (>1 A cm-2) to evaluate the electrocatalytic performance under simulated industrial conditions. This ensures objective and authentic assessments of the catalyst application potential. Throughout the following sections, we illustrate the application of interface chemical engineering on different length scales in designing diverse electrocatalyst materials. We rely on in situ characterization techniques to gain a profound understanding of the mechanisms behind the HER and OER. Additionally, we describe the development of both acidic and alkaline MEA electrochemical reactors to enhance the precision of electrocatalytic performance evaluation. Finally, we provide a concise overview of the challenges and opportunities in this field.

Surface reconstruction of La0.6Sr0.4Co0.8Ni0.2O3-δ perovskite nanofibers for oxygen evolution reaction

Perovskites have become promising alternatives to precious metal-catalyzed oxygen evolution reaction (OER). Herein, we report the synthesis of several perovskite nanofibers, specifically La0.6Sr0.4CoxNi1-xO3-δ (LSCN), and investigate their electrocatalytic water oxidation activity in alkaline electrolytes. La0.6Sr0.4Co0.8Ni0.2O3-δ (LSCN-0.8) is selected and immersed in an aqueous NaBH4 solution for 1 h for surface reconstruction. The perovskite nanofibers' electrocatalytic OER activity and stability are rigorously evaluated using a standard three-electrode system. Results reveal that even a slight Co substitution for Ni content within the LSCN perovskite structure has a notable impact on electrocatalytic activity. Moreover, LSCN-0.8 exhibits an overpotential of 363 mV at 20 mA cm−2 in 1 M KOH. However, significant improvement is observed after the surface reconstruction process. The optimized LSCN-0.8 (now called LSCN-2) displays the lowest OER overpotential (320 mV) under the same conditions. Furthermore, the LSCN-2 nanostructure demonstrates exceptional electrode stability, as evidenced by only a slight decrease in electrocatalytic performance during 5000 cycles of linear sweep voltammetry.

Modulating nickel-iron active species via dealloying to boost the oxygen evolution reaction.

The surface structure and composition of pre-catalysts play a critical role in the surface reconstruction process toward active species during the anodic oxygen evolution reaction (OER). Surface modified methods can accelerate the OER process of alloy ribbons, but the understanding of pre-catalysts and the structure/reactivity of the reconstruction (active) species is still insufficient. Herein, we report a two-step dealloyed Ni-Fe-P alloy ribbon as a highly efficient OER electrocatalyst. By adjusting the surface-derived component, we could regulate Ni/Fe hydroxide active species on the Ni-Fe-P alloy ribbon, enhancing the OER performance. The oxidation and release of P driven by dealloying plays a key role in constructing optimal β-NiOOH/FeOOH catalytic species on Ni-Fe-P. The optimal β-NiOOH/FeOOH active species enables Ni-Fe-P alloy to obtain a 104 mV of reduction in overpotential (at 10 mA cm-2) and a 78-fold increase in current density (at overpotential: 300 mV) compared to undealloyed Ni-Fe-P. Our work provides valuable insights into the relationship between the surface structure/composition of alloy bulk electrocatalysts and surface-reconstructed species and a rational design of a surface treatment process.

Enhancing Oxygen Evolution Reaction Performance: Electrochemical Activation of the Biphasic CoNi/Zn(Fe,Al,Cr)2O4 via Controlled Aluminum Leaching Facilitated Surface Reconstruction

AbstractGiven that the oxygen evolution reaction (OER) faces challenges due to its sluggish kinetics, development of efficient and robust OER catalytic electrodes is critical for reducing the cost of hydrogen production through electrochemical water splitting. In this study, a biphasic CoNi/Zn(Fe,Al,Cr)2O4 coating, characterized by a densely organized stalagmite‐like microarray structure, is deposited on a commercial pure titanium plate, creating an exceptionally effective OER catalytic electrode. The formation of numerous metal/spinel oxide heterogeneous interfaces is demonstrated to enhance its electron transfer ability and conductivity. At high potentials, aluminum leaching and lattice oxygen consumption can facilitate deep surface reconstruction of highly active Fe‐doped CoNiOOH phase inducing electrochemical activation, further optimizing thermodynamic barrier of the fundamental reaction step. Ultimately, this electrode showcases exceptional OER catalytic performance (low overpotential of 248 and 335 mV to deliver the current density of 10 and 100 mA cm−2) compared to commercial IrO2 catalyst (overpotential of ≈310 mV at 10 mA cm−2). Moreover, it demonstrates high current stability sustaining a current density of 500 mA cm−2 for 100 h. This work deepens the comprehension of the surface reconstruction process in OER and, more broadly, introduces a new avenue for designing and enhancing the performance of catalytic materials.

Proton Shuttle-Assisted Surface Reconstruction toward Nonpolar Facets-Terminated Zinc-Blende CdSe/CdS Core/Shell Quantum Dots.

Surface reconstruction can rearrange the surface atoms of a crystal without the need of growth processes and has the potential to synthesize crystals with novel morphologies and facets that cannot be obtained through regular synthesis. However, little is known about the molecular mechanisms of the surface reconstruction process. Here, utilizing surface reconstruction, we report the synthesis of nonpolar facets (110) facets)-terminated dodecahedral zinc-blende CdSe/CdS core/shell quantum dots. The morphology transformation is achieved by first fully exchanging the cadmium carboxylate ligand with oleylamine and then undergoing surface reconstruction. The surface reconstruction-induced morphology transformation is confirmed by transmission electron microscopy and absorption spectroscopy. Details of kinetic experiments and simulation results demonstrated that successful surface reconstruction must be assisted by a proton shuttle. Except for the first report on zinc-blende quantum dots terminated with (110) facets, the surface reconstruction aided by the proton shuttle offers valuable insights for devising methods to regulate the properties of nanocrystals.

Solid redox equilibrium via d-band centers regulation in the MoS2/Ni3S2 heterojunction for efficient selective oxidation of 5-hydroxymethylfurfural

The 5-hydroxymethylfurfural electrocatalytic oxidation reaction (HMFOR), in coupling with the hydrogen evolution reaction (HER), can replace the kinetically slow anodic oxygen evolution reaction (OER) to produce high value oxides and hydrogen. However, the commonly employed Ni-based electrocatalyst exhibits an unsatisfied performance due to the existence of OER. Here, we design and synthesize the Ni3S2/MoS2/NiMoO4 catalyst for efficient and stable HMFOR reaction. Through the in situ Raman spectroscopy, we demonstrate that the NiIII–OOH formed during the surface reconstruction process is the real reactive species for HMFOR. Moreover, the density functional theory results show that the upward shift of d-band centers in the reconstructed NiOOH/MoS2 is beneficial for the HMF adsorption and guarantees the smooth progression of redox equilibrium reactions. As a result, the prepared electrocatalyst shows a good HMFOR electrocatalytic performance in terms of selectivity (99.2%), conversion (96.7%), and Faraday efficiency (96.5%).

Architecting the metal-nonmetal oxide layers for boosting the oxygen-evolving intrinsic activity of amorphous alloy

Designing high-efficiency and freestanding electrocatalysts hold immense importance in addressing the limitations of powdered electrocatalysts and accelerating the sluggish kinetics of the oxygen evolution reaction (OER) in advancing energy technologies. While dealloyed amorphous ribbons have been shown to be active and self-supporting electrocatalysts toward OER, the underlying enhancement mechanism remains unclear. Here, we developed a dealloyed Ni-Fe-B-Si-P amorphous electrocatalysts with a mixed oxide layer (including oxo-anions: phosphate, silicate, and borate). The dealloyed oxide layer optimizes the surface properties and chemical local environment of the amorphous ribbon, then shortens the multistep evolution path (Ni0 → Ni2+ → Ni3+ → Ni4+) toward Ni4+ species during the surface reconstruction process and decreased energy barriers for the dealloyed Ni-Fe-B-Si-P electrocatalyst during OER. Benefiting from the changes, the dealloyed Ni-Fe-B-Si-P enables a 56-fold increase in current density (at overpotential: 320 mV) and an 8-fold increase in turnover frequency values compared to undealloyed Ni-Fe-B-Si-P, demonstrating the major effect of the intrinsic activity on the OER performance of the dealloyed ribbon. This work sheds light on the enhancement mechanism of amorphous bulk electrocatalysts and offers valuable insights into the rational design of amorphous components and surface treatment processes.

Accelerated Surface Reconstruction through Regulating the Solid-Liquid Interface by Oxyanions in Perovskite Electrocatalysts for Enhanced Oxygen Evolution.

A comprehensive understanding of surface reconstruction was critical to developing high performance lattice oxygen oxidation mechanism (LOM) based perovskite electrocatalysts. Traditionally, the primary determining factor of the surface reconstruction process was believed to be the oxygen vacancy formation energy. Hence, most previous studies focused on optimizing composition to reduce the oxygen vacancies formation energy, which in turn facilitated the surface reconstruction process. Here, for the first time, we found that adding oxyanions (SO42-, CO32-, NO3-) into the electrolyte could effectively regulate the solid-liquid interface, significantly accelerating the surface reconstruction process and enhancingoxygen evolution reaction (OER) activities. Further studies indicated that the added oxyanions would adsorb onto the solid-liquid interface layer, disrupting the dynamic equilibrium between the adsorbed OH- ions and the OH- ions generated during surface reconstruction process. As such, the OH- ions generated during surface reconstruction process could be more readily released into the electrolyte, thereby leading to an acceleration of the surface reconstruction. Thus, it was expected that our finding would provide a new layer of understanding to the surface reconstruction process in LOM-based perovskite electrocatalysts.

Accelerated Surface Reconstruction through Regulating the Solid‐Liquid Interface by Oxyanions in Perovskite Electrocatalysts for Enhanced Oxygen Evolution

AbstractA comprehensive understanding of surface reconstruction was critical to developing high performance lattice oxygen oxidation mechanism (LOM) based perovskite electrocatalysts. Traditionally, the primary determining factor of the surface reconstruction process was believed to be the oxygen vacancy formation energy. Hence, most previous studies focused on optimizing composition to reduce the oxygen vacancy formation energy, which in turn facilitated the surface reconstruction process. Here, for the first time, we found that adding oxyanions (SO42−, CO32−, NO3−) into the electrolyte could effectively regulate the solid–liquid interface, significantly accelerating the surface reconstruction process and enhancing oxygen evolution reaction (OER) activities. Further studies indicated that the added oxyanions would adsorb onto the solid–liquid interface layer, disrupting the dynamic equilibrium between the adsorbed OH− ions and the OH− ions generated during surface reconstruction process. As such, the OH− ions generated during surface reconstruction process could be more readily released into the electrolyte, thereby leading to an acceleration of the surface reconstruction. Thus, it was expected that our finding would provide a new layer of understanding to the surface reconstruction process in LOM‐based perovskite electrocatalysts.

EXPLICIT ANNOTATED 3D-CNN DEEP LEARNING OF GEOMETRIC PRIMITIVES INSTANCES

AbstractIn reengineering technical components, the robust automation of reverse engineering (RE) could overcome the need for human supervision in the surface reconstruction process. Therefore, an enhanced computer-based geometric reasoning to derive tolerable surface deviations for reconstructing optimal surface models would promote a deeper geometric understanding of RE downstream processes. This approach integrates advanced surface information into a deep learning-based recognition framework by explicitly labeling geometric outliers and subsurface boundaries. For this purpose, a synthetic dataset is created that morphs nominal surface models to resemble the macroscopic surface pattern of physical components. For the detection of regular geometry primitives, a 3D-CNN is used to analyze the voxelized components based on signed distance field data. This explicit labeling approach enables surface fitting to derive suitable shape features that fulfill the underlying surface constraints.

Prediction of surface reconstructions using MAGUS.

In this paper, we present a new module to predict the potential surface reconstruction configurations of given surface structures in the framework of our machine learning and graph theory assisted universal structure searcher. In addition to random structures generated with specific lattice symmetry, we made full use of bulk materials to obtain a better distribution of population energy, namely, randomly appending atoms to a surface cleaved from bulk structures or moving/removing some of the atoms on the surface, which is inspired by natural surface reconstruction processes. In addition, we borrowed ideas from cluster predictions to spread structures better between different compositions, considering that surface models of different atom numbers usually have some building blocks in common. To validate this newly developed module, we tested it with studies on the surface reconstructions of Si (100), Si (111), and 4H-SiC(11̄02)-c(2×2), respectively. We successfully gave the known ground states, as well as a new SiC surface model, in an extremely Si-rich environment.

Controllable surface reconstruction of copper foam for electrooxidation of benzyl alcohol integrated with pure hydrogen production

AbstractElectrocatalytic water splitting that is coupled with electrocatalytic chemical oxidation is considered as one of the promising methods for efficiently obtaining hydrogen energy and fine chemicals. Herein, we focus on an electrochemical redox activation strategy to rationally manipulate the microstructure and surface valence states of copper foam (CF) and boost the corresponding performance towards electrocatalytic benzyl alcohol oxidation (EBA), accompanied by the efficient hydrogen production. Correspondingly, the Cu(II)‐dominated species are gradually formed on the CF surface with the dissolution and redeposition of copper in the suitable potential range. The new species containing Cu2O, CuO, and Cu(OH)2 during surface reconstruction process of the CF were confirmed by multiple characterization techniques. After 220‐cycled activation (CF‐220), the activated CF achieves an increase of current density for EBA in anode from 9.5 for the original CF to 29.3 mmol/cm2, while the pure hydrogen yield increases threefold than that of the original CF at 1.5 VRHE. The produced new species can endow the CF‐220 with abundant acidity sites, which can enhance the adsorption toward Lewis‐basicity benzyl alcohol, confirmed by NH3‐temperature‐programmed desorption. In situ Raman result further reveals that the as‐produced CuO, Cu(OH)2, and Cu(OH)42− are the main active species toward the EBA process.

Origin of Surface Reconstruction in Lattice Oxygen Oxidation Mechanism Based‐Transition Metal Oxides: A Spontaneous Chemical Process

AbstractA fundamental understanding of surface reconstruction process is pivotal to developing highly efficient lattice oxygen oxidation mechanism (LOM) based electrocatalysts. Traditionally, the surface reconstruction in LOM based metal oxides is believed as an irreversible oxygen redox behavior, due to the much slower rate of OH− refilling than that of oxygen vacancy formation. Here, we found that the surface reconstruction in LOM based metal oxides is a spontaneous chemical reaction process, instead of an electrochemical reaction process. During the chemical process, the lattice oxygen atoms were attacked by adsorbed water molecules, leading to the formation of hydroxide ions (OH−). Subsequently, the metal‐site soluble atoms leached from the oxygen‐deficient surface. This work also suggests that the enhancement of surface hydrophilicity could accelerate the surface reconstruction process. Hence, such a finding could add a new layer for the understanding of surface reconstruction mechanism.

Origin of Surface Reconstruction in Lattice Oxygen Oxidation Mechanism Based-Transition Metal Oxides: A Spontaneous Chemical Process.

A fundamental understanding of surface reconstruction process is pivotal to developing highly efficient lattice oxygen oxidation mechanism (LOM) based electrocatalysts. Traditionally, the surface reconstruction in LOM based metal oxides is believed as an irreversible oxygen redox behavior, due to the much slower rate of OH- refilling than that of oxygen vacancy formation. Here, we found that the surface reconstruction in LOM based metal oxides is a spontaneous chemical reaction process, instead of an electrochemical reaction process. During the chemical process, the lattice oxygen atoms were attacked by adsorbed water molecules, leading to the formation of hydroxide ions (OH-). Subsequently, the metal-site soluble atoms leached from the oxygen-deficient surface. This work also suggests that the enhancement of surface hydrophilicity could accelerate the surface reconstruction process. Hence, such a finding could add a new layer for the understanding of surface reconstruction mechanism.