The petroleum refining industry faces increasing challenges in processing sulfur-rich crude oils while meeting stringent environmental regulations. Increasing the metal loading is the most straightforward approach to enhancing catalyst activity. However, under high metal loading conditions, the catalyst tends to form a significant amount of isolated low-activity NiSx and NiOx species. This study presents an effective " sulfidationoxidation-secondary sulfidation" reconstruction process to enhance the hydrogenation performance of high-loading sulfide NiMoW/SiO2 catalysts. The migration of active species on the metal surface was induced through high-temperature calcination and sulfur-oxygen transformation processes, leading to the conversion of isolated NiSx and NiOx species into a distinctive NiMoWS/NiSx-SiO2 composite active phase, with NiSx functioning as a secondary support. Extensive characterization using XRD, HRTEM-EDS, XPS, and DFT calculations revealed that this structural modification substantially increased metal dispersion, sulfidation degree, and hydrogen spillover effects. The optimized NiMoW-300(S) catalyst displayed excellent hydrodesulfurization (HDS) activity and hydrogenation selectivity, with a relative volumetric activity (RVA) 2.49 times higher than that of the conventional NiMo/gamma-Al2O3 catalyst, while also demonstrating outstanding stability.

Ruthenium dioxide (RuO2) is regarded as a promising alternative to iridium-based catalysts for the oxygen evolution reaction (OER) in proton exchange membrane water electrolyzers (PEMWEs) owing to its high intrinsic activity and relatively lower cost. Nevertheless, the activity-stability trade-off induced by competing reaction pathways under harsh acidic conditions severely restricts the large-scale industrial application of RuO2-based catalysts. An in-depth understanding of these reaction pathways is therefore critical for the precise structural design and performance optimization of RuO2-based catalysts. This review systematically summarizes three mainstream OER mechanisms of RuO2 catalysts in acidic environments, namely, the adsorbate evolution mechanism (AEM), lattice oxygen-mediated mechanism (LOM), and oxide path mechanism (OPM). Subsequently, the recent advances in reaction pathway regulation strategies, such as element doping, heterostructure engineering, and defect engineering, are highlighted with the aim to overcome the activity-stability trade-off. Furthermore, the critical role of in situ characterization technologies during the OER process in identifying the reaction intermediates and dynamic structural evolution is discussed. Finally, the remaining challenges and future directions for achieving precise control and industrial-scale applications are outlined, providing a foundation for designing high-performance, durable RuO2-based catalysts for sustainable hydrogen production.

NH4F serves as a critical morphology-regulating agent to effectively optimize the catalyst OER activity. Current research indicates that its regulatory mechanism centers on the coordination effect of F. However, the complexity introduced by F doping during hydrothermal processes hinders further analysis of its regulatory effect on the catalyst. Therefore, a two-step hydrothermal strategy is adopted herein, by introducing F at different stages to differentiate coordination doping mechanism. Experimental results indicate that the efficient Fe incorporation driven by the coordination effect of F triggers lattice structure transformation of the catalyst, thereby greatly enhancing its structural reconstruction capability. Interestingly, this study reveals that the coordination effect of F enables efficient Fe incorporation while inducing targeted F doping. The targeted F doping drives the formation of a O-Co-F structure in the catalyst during electrochemical reconstruction. This weakens the covalent character of Co-O bonds and optimizes the adsorption capability of the catalyst toward *OH intermediates. Consequently, F-CoFe exhibits an overpotential of only 296 mV at a current density of 100 mA cm-2, and can operate stably for 100 h under conditions of 1 A cm-2. This work reveals the critical role of F coordination doping in tailoring the catalyst structure, which paves the way for the rational application of NH4F in hydrothermal morphology control.

Molybdenum carbide (Mo2C) is recognized as a promising electrocatalyst for water splitting owing to its platinum-like electronic structure. However, its practical application is severely impeded by the agglomeration of active sites, excessively strong MoH bonding, and poor resistance to oxidation and corrosion. To address these limitations, we propose a "template size control-multimetal coordination" strategy to fabricate nitrogen-doped carbon-supported CoNi-modified Mo2C hollow microspheres (CoNi@Mo2C/C). By rationally tuning the template architecture, an optimal balance between graphitic carbon and carbon defects is achieved, enabling rapid electron transport while preserving a high density of active sites. The CoNi bimetallic components were introduced to downshift the Mo d-band center, which weakened the MoH bond strength and boosted the electrocatalytic activity. Moreover, Co and Ni spontaneously form an active oxyhydroxide phase through self-oxidation, which effectively protects Mo2C from oxidative corrosion and leaching, thereby substantially improving operational stability. Among the series, the CoNi@Mo2C/C catalyst synthesized with a 500 nm polystyrene (PS) template exhibits exceptional bifunctional activity and durability in 1.0 M KOH. At a current density of 10 mA·cm-2, the catalyst delivers an overpotential of 73.2 ± 2.2 mV for the hydrogen evolution reaction (HER), 212.8 ± 2.8 mV for the oxygen evolution reaction (OER), and a full-cell voltage of 1.515 V for overall water splitting. This work not only offers critical experimental insights but also establishes a theoretical foundation for the rational design of high-performance non-precious-metal electrocatalysts.

With the increasing heavy and inferior quality of global oil resources, the efficient utilization of crude oil has become a critical challenge to be solved in the energy field. This work intends to propose a feasible way of crude oil pretreatment in the refining process. A comparison of the comprehensive performance differences between thermal processing (TP) and slurry phase hydroupgrading (SPH) treatments revealed that SPH had a great upgrading effect for Arabian heavy crude oil under 390 degrees C and oil-soluble MoS 2 catalyst. Compared with the feedstock, the asphaltene content of TP product increased by 13.2 wt%, that in SPH product dropped by about 19.8 wt%. And the total distillate yield (<= 540 degrees C) of SPH increased by 4.4 wt% compared to the TP. The results of SARA separation and X-Ray Diffraction (XRD) showed that SPH can not only inhibit the occurrence of free radical reactions, but also dissociate the original asphaltene. The detailed composition of the processed samples was characterized by gas chromatography-mass spectrometry (GC-MS) and electrospray ionization orbitrap mass spectrometry (ESI Orbitrap MS) to explore the molecular transformation mechanism of different processes. There are a considerable number of -S- bonds in asphaltene as important structural connection hubs. The process of SPH can promote the production of light hydrocarbons while effectively removing heteroatom compounds. Finally, we considered that it is necessary to carry out the SPH pretreatment for Arabian heavy crude oil. (c) 2025 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ncnd/4.0/).

ABSTRACT The synergistic design combining thermodynamic and kinetic factors is critical for breaking bottlenecks in achieving both high efficiency and selectivity in electrocatalytic reactions. However, hindered by characterization limits, the interfacial supply and migration of reactants and products kinetically promoted by the interfacial hydrogen bond network are usually neglected. Owing to recent technological breakthroughs, there are significant progress in hydrogen‐bond‐network‐regulated electrocatalysis, heralding a new era of hydrogen‐bond‐directed electrocatalysis. This review first presents the fundamentals of interfacial hydrogen bond networks with an emphasis on the Grotthuss mechanism for proton (H + ) /hydroxide (OH − ) transfer and water (H 2 O) supply. Then it elucidates mass transport mechanisms of key species directly involved in the rate‐determining steps of many vital reactions through a hydrogen bond network. The key factors governing the efficient regulation of hydrogen bond networks, such as electronic structure, surface functionalization, and electrolyte composition, have been systematically sorted out for electrocatalytic reactions including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), carbon dioxide reduction reaction (CO 2 RR), and nitrate reduction reaction (NO 3 − RR). Finally, future research focused on modulating interfacial hydrogen bond network under industrial operating conditions are outlooked, aiming to advance the field of aqueous electrocatalysis for a sustainable future driven by renewable‐energy‐driven green resource cycling.

Hydrazine-assisted mixed-alkaline seawater electrolysis provides an environmentally friendly platform that can both remediate toxic hydrazine and produce hydrogen autonomously. However, complex multi-step processes of dehydrogenating hydrazine intermediates often lead to sluggish reaction kinetics, which pose significant challenges for efficient catalysis. We propose an innovative strategy of exploiting overlap between 3d orbital of Ag and p orbital of terephthalic acid (TPA) ligands to form strong covalent bonds. The covalent nature of bonds in metal-organic framework (MOF) promotes delocalization of electrons between Ag nodes and Co/Fe sites, thereby accelerating electron transfer rate. A straightforward, one-step hydrothermal process has been adopted to realize the in-situ growth of silver-doped cobalt/iron metal-organic framework @Nickel Foam (AgCoFe-MOF@NF) nanoflakes on nickel foam. The integrated hydrazine-water splitting device based on AgCoFe-MOF@NF operates at a low potential of just 0.72 V at current density of 100 mA·cm−2 over 100 h, which is significantly lower than 2.2 V all water splitting voltage of coupled cells. Ag incorporated into MOF maintains exceptional stability of exceeding 100 h, even when operating in a seawater. This study sheds light on the unsaturated coordination in controlling N–H bond cleavage. It provides valuable insights and practical strategies for optimizing the dehydrogenation of intermediates in hydrazine oxidation reaction (HzOR) and similar reactions.

Precisely regulating the electronic structures of electrocatalysts to achieve an optimum hydroxide binding energy (OHBE) and hydrogen binding energy (HBE) is crucial to the hydrogen evolution reaction (HER). Hence, from the perspective of Hammer-Norskov D-band model and molecular orbital theory, we introduced W sites and cation vacancy (V-Zn) by coordination polymer strategy and self-templating method to exactly tailor the electronic structures of ultrafine Rh2P (WZn-Rh2P) with a simultaneously decreased anti-bonding filling (ABF) as well as increased energy-level alignment (ELA) between the adsorbed hydroxide (*OH) states and surface Rh D-band, thus realizing the enhanced OHBE. Meanwhile, the increased ABF and decreased ELA (with *H) brings weakened HBE, which makes favorable performance of the catalyst in both acidic and alkaline extremes. As a result, WZn-Rh2P requires the smallest overpotentials of 22 and 84 mV at 10 mA cm(-2) in alkaline and acidic electrolytes compared to Pt/C benchmark. Theoretical calculation illuminated the relationship between OHBE/HBE and W/V-Zn. Furthermore, the lifetime of W-Zn-Rh2P at 200 mA cm(-2) is more than 200 h (alkaline) and 500 h (acidic), ascribing to the introduced metal-oxygen sites and the strong metal anchoring of carbon supports. This work provides a new approach from the perspective of energy levels and orbitals for the precise control of the electronic structure of electrocatalysts.

Transition metal sulfides (TMSs) are promising for oxygen evolution reaction (OER) owing to tunable electronic structure and high conductivity, but suffer from limited activity and stability. NiFeOOH can generate oxygen vacancies to modulate electronic structure and provide active sites, yet its poor conductivity restricts overall efficiency. In this study, a heterojunction catalyst (NS/NFC) consisting of crystalline Ni3S2 and amorphous NiFeCrOOH was successfully synthesized using a combination of hydrothermal synthesis and subsequent electrochemical activation. Synergistic enhancement of catalytic performance was achieved through engineering of the amorphous/crystalline interface. Cr3 + directly regulates Fe sites and indirectly influences Ni sites through charge rearrangement, achieving differentiated electronic modulation, while the heterojunction enhances charge transport and active site exposure. Owing to these synergies, NS/NFC exhibits overpotentials of 255 and 314 mV at 100 and 1000 mA cm−2, respectively, with a slight increase of 14 mV in overpotential after 120 h of stability testing. This work demonstrates that amorphous/crystalline heterostructure design effectively integrates the high active-site density of amorphous phases with the superior conductivity of crystalline counterparts, offering a promising strategy for developing efficient and durable non-precious-metal OER catalysts.

This study tackles the challenge of treating high-oil (>= 90 mg/L) and high-salinity (Cl- >= 6900 mg/L) oilfield-produced water for green hydrogen production. An integrated technology combining electrochemical cascade purification (EDCF: electro-demulsification-coagulation-flotation) with alkaline water electrolysis is developed. The EDCF process effectively reduces oil, suspended solids, and turbidity to <10 mg/L, <20 mg/L, and <20 NTU, respectively, meeting stringent feedwater criteria for electrolysis. An asymmetric electrolysis strategy employing a nickel felt anode/Raney nickel cathode system achieves a low cell voltage of 1.856 V at 1 A/cm(2) in 6 M KOH at 85 degrees C, with 96.58% H-2 purity. Crucially, separate anolyte/catholyte (0.5/6 M KOH) mitigates Cl- corrosion, enabling stable 240 h operation (96.66% +/- 0.5% H-2 purity) in a duplex steel electrolyzer. The work establishes comprehensive boundary conditions for scalable hydrogen production from treated produced water.

As hydrogen energy and refueling stations develop, higher requirements are imposed on hydrogen compressor performance. Hydraulic-driven hydrogen compressors are preferred for future stations due to pressure-resistant start-stop, wide pressure range, and strong adaptability. However, theoretical studies on this type of compressor remain scarce, limiting optimal design guidance. To clarify the pressurization mechanism, flow and pressurization characteristics of hydraulic-driven hydrogen compressors are investigated under dynamic gas valve effects via CFD dynamic grid technology. Based on simulation results, valve structure is optimized to enhance pressurization stability. Results indicate hydrogen movement and turbulence in cylinder closely relate to piston motion and valve opening/closing. Significant flow and pressure fluctuations occur due to hydrogen backflow at the end of suction/discharge. After optimization, maximum backflow decreases by 25.18% and pressure fluctuation range by 49.09% (valve core mass 20 g, lift 2 mm). Valve structure optimization improves stability and discharge capacity for hydraulic-driven hydrogen compressors.

The slow hydrogen proton transfer rate during the oxygen evolution reaction (OER) process results in sluggish kinetics of proton desorption and local acid corrosion of active sites, which significantly impairs catalytic activity and stability, especially at high current density. In this work, an expedited proton removal has been realized using tetrahydroxy-1,4-benzoquinone (THQ) as a proton transfer relay. THQ-inserted NiFeOOH (NiFeOOH/THQ) through a sample one-step hydrothermal method. THQ not only effectively reduces the electron cloud density around Ni/Fe active sites as a strong electron-withdrawing ligand, but also connects the catalyst/electrolyte interface hydrogen bond to accelerate proton transfer enriched on the catalytic surface. NiFeOOH/THQ exhibited enhanced OER activity, with an overpotential of only 260 mV at 100 mA cm-2, which is considerably lower than that of NiFeOOH (320 mV). The Tafel slope measured 22.98 mV dec-1, indicating the accelerated OER kinetics. Furthermore, NiFeOOH/THQ can maintain stable operation at 100 mA cm-2 for 250 h. This improved OER performance is attributed to the formation and robustness of highly active Ni3+ sites and mitigated local acid corrosion stemming from regulated electron/proton transfer. This study presents a novel design strategy for advanced electrocatalysts by facilitating rapid proton neutralization and stabilizing active sites through ligand intercalation.

Catalyst deactivation caused by metal dissolution has constrained high-performance nickel-iron-based electrocatalyst development. This study innovatively repurposes metal dissolution as a structural design strategy. Crdoped NiFe-layered double hydroxide is synthesized, and a dual-activation strategy with descending alkali concentration enables relay Fe/Cr dissolution, constructing a dual anion-cation vacancy catalyst. During preactivation, Fe dissolves readily to form cation vacancies, whereas Cr, with its low-spin t2g3 configuration, stabilizes the framework via a more robust octahedral structure. During electro-activation, oxygen vacancies are formed while Cr relay dissolution creates cation vacancies. The dissolved Cr3+ oxidizes to CrO42 , which partly readsorbs on the surface. These vacancies and adsorbed anions synergistically tune active-site electronics, boosting OER performance. The resulting dR-NiFeCr-LDH catalyst requires overpotentials of only 235 and 284 mV to achieve current densities of 100 and 1000 mA cm 2, respectively. It also maintains stable operation for over 120 h under a high current density of 1 A cm 2 in a strongly corrosive 1 M KOH environment.

Electrolyzing seawater for hydrogen production is a promising route toward energy transition, yet its efficiency is limited by sluggish water dissociation, hydrogen desorption kinetics, and cathode-side precipitation issues. To address these challenges, a highly efficient hydrogen evolution electrocatalyst was developed by constructing a Pt/NiS structure interconnected through S bridge bonds, enabling strong synergistic electron transfer. In situ characterizations and theoretical analyses reveal that the S bridges modulate charge distribution between NiS and Pt and enhance strong metal-substrate interactions (SMSI), which disrupt rigid hydrogen-bond networks, accelerate water dissociation on NiS, and facilitate H* transfer to Pt. Furthermore, in neutral seawater, the disrupted hydrogen-bond network also increases water mobility and lowers bubble surface tension, promoting the formation and release of smaller bubbles and preventing active-site blockage by Mg/Ca hydroxide precipitates. As a result, the catalyst achieves excellent stability in alkaline and neutral seawater. In an anion exchange membrane water electrolyzer (AEMWE), the Pt/NiS||S-NiFe LDH system delivers a low cell voltage of 1.71 V at 100 mA cm-2 and a competitive hydrogen production cost of $1.07 GGE-1, demonstrating its outstanding activity, stability, and efficiency.

Lead halide perovskites are promising for artificial photosynthesis but suffer from aqueous instability. Here, we stabilize CsPbI3 quantum dots within a hydrophobic chlorine-functionalized covalent organic framework through multisite atomic-chlorine passivation, forms dual Cl-Pb coordination and Cl-I halogen bonding at the interface. This suppresses ionic migration while creating a gas-solid-liquid triphase interface for enhanced O2 diffusion. The resulting S-scheme heterojunction spatially separates carriers to concurrently drive two-electron oxygen reduction and water oxidation for H2O2 synthesis without sacrificial agents. The system achieves production rates of 20.37 mmol h-1 g-1 in seawater, with a solar-to-chemical conversion efficiency of 1.38%, and operates stably for 20 h. Importantly, natural sunlight tests yield 11.7 mmol L-1 H2O2 in 10 h. Mechanistic studies confirm synergistic interfacial charge transfer and dual-reaction pathways via both oxygen reduction and water oxidation. This work demonstrates an approach for robust perovskite-based photocatalysts toward solar-driven chemical synthesis from seawater.

As an efficient green hydrogen production technology, water electrolysis promotes global energy transition and carbon neutrality. Poor catalytic activity and durability restrict its energy efficiency and industrial application. Strain engineering effectively regulates electronic structures, reaction kinetics and lattice stability to address the key issues of water splitting. Different from previous reviews that merely focused on single lattice strain and activity-oriented mechanism analysis, while ignoring the surface stress effect, HER/OER mechanistic differences, and industrial stability demands, we herein conduct a systematic review of state-of-the-art advances in strain engineering applied to the rational design of electrocatalysts for the hydrogen evolution reaction and oxygen evolution reaction. The unique strengths of strain regulation in enhancing catalytic activity and stability are elaborated, and the intrinsic modulation mechanisms behind different strain effects are generalized. Meanwhile, some representative catalysts based on lattice strain engineering and surface stress regulation are analyzed and discussed. Finally, the challenges, opportunities and research trends of strain modulation for high-performance water-splitting electrocatalysts are highlighted, laying a theoretical foundation for the rational design and fabrication of advanced electrocatalytic materials.

The structural design and electron modulation of the electrocatalyst for the oxygen evolution reaction (OER) are a crucial part of a high-efficiency electrochemical water splitting system. Metal-organic frameworks (MOFs) composed of metal sites and ligands are promising catalysts due to their unique coordination structure and facile electron transfer, which can effectively modulate and stabilize the catalytically active sites at OER interface. This article systematically reviews the research progress of MOF-based OER electrocatalysts and the corresponding catalytic mechanisms for alkaline OER. Firstly, the adsorption evolution mechanism (AEM) and lattice oxygen participation mechanism (LOM) of OER are introduced, and the differences in reaction pathways among different metal electrocatalysts are analyzed. Subsequently, the article summarizes four types of MOF materials and designing strategies, with a focus on investigating the effect of reconstruction on MOF-based OER electrocatalysts from the perspectives of active center regulation and ligand optimization. In addition, the self-healing capability of reconstructed MOFs and the framework stability under high-current and strong alkaline conditions are discussed, which offer valuable insights into the long-term performance of these catalysts. Finally, this paper summarizes the industrial applications of MOF-based OER electrocatalysts and outlines their future development prospects.

Stringent environmental regulations and the need to process heavy, sour crudes are driving the development of advanced hydrodesulfurization (HDS) catalysts, particularly Ni-promoted Mo/W sulfide catalysts. Although the promotional role of Ni in sulfide HDS catalysts is well recognized, the origin of activity suppression under Ni-rich conditions remains unclear. In this work, a series of high-loading NiMoW/SiO2 catalysts with varying Ni contents were investigated to clarify why further Ni addition leads to activity suppression in the HDS reaction under Ni-rich conditions. Combined Py-IR, EPR, Raman, XPS, and DFT analysis reveal that the key factor is the balance between -SH and coordinatively unsaturated sites (CUS) on the sulfide surface. An appropriate Ni content increases the abundance of catalytically effective sites while maintaining favorable -SH/CUS matching, leading to the highest HDS activity for Ni1Mo1W1. In contrast, excess Ni causes a continuous increase in the relative abundance of -SH species without a corresponding effective generation of additional CUS sites, thereby disrupting the -SH/CUS balance and suppressing DBT conversion. The optimized Ni1Mo1W1 catalyst also exhibited stable performance over five cycles and a 1.47-fold higher relative volume activity than the industrial NiMo/γ-Al2O3 reference catalyst (8 MPa, 300 °C), and good stability during a 360 h real-oil hydrotreating test. This work identifies -SH/CUS imbalance as a major origin of activity suppression under Ni-rich conditions in NiMoW catalysts.

Unlocking the full potential of CoFe-based oxygen evolution reaction (OER) electrocatalysts is currently impeded by the dual challenges of sluggish intrinsic kinetics and thermodynamic instability caused by severe iron leaching. Herein, we report a synergistic strategy combining molten salt synthesis and fluoride calcination to engineer F-doped CoFe-based nanosheets (Fe,F-CoNH). The optimized Fe,F-CoNH catalyst demonstrates superior OER performance, requiring an overpotential of only 241 mV to reach 100 mA cm-2. Notably, it exhibits exceptional stability for 100 h at an industrial-level current density of 1 A cm-2 in both three-electrode configurations and anion exchange membrane water electrolyzers (AEMWEs). Mechanistic investigations reveal that F-doping creates defect-rich crystalline-amorphous interfaces and modulates the electronic structure of Co/Fe sites via strong electronic interactions. This dual effect optimizes intermediate adsorption energies while the robust metal-fluoride (M-F) bonds significantly suppress Fe leaching. Consequently, this work presents a promising molten salt-fluoride strategy for constructing robust, high-performance OER electrocatalysts for practical applications.