Phosphating Process Research Articles

Dual-metal-organic-framework derived CoP/MoP hybrid as an efficient electrocatalyst for acidic and alkaline hydrogen evolution reaction

Searching for efficient and cost-effective electrocatalysts for hydrogen evolution reaction (HER) is significantly desirable and challenging. Herein, N, P co-doped carbon-encapsulated CoP/MoP hybrid (CoP/MoP@NPC) is fabricated using dual-metal–organic-framework (dual-MOF) as precursor by a simple one-step phosphating process. When applied as an electrocatalyst toward the HER, the as-designed CoP/MoP@NPC hybrid shows efficiently catalytic performance with a lower overpotential of 183 mV to deliver a current density of 10 mA cm−2, smaller Tafel slope of 53.3 mV dec-1 as well as long-time stability for 10 h in 0.5 M H2SO4 owing to the distinctive component and structural advantages. Furthermore, the electrode material also displays enhanced electrocatalytic HER activity in alkaline media. Importantly, this work provides an effective and feasible route for the construction of bimetallic phosphide electrocatalysts toward hydrogen production.

Development of WEF-P Nexus based on product-supply chain: A case study of phosphorous fertilizer industry in Morocco

The aim of this study was to analyze various sustainability strategies for phosphate and phosphorous fertilizer production systems from the perspective of their holistic impacts on water, energy, and CO2 emissions. The study was conducted using the Water-Energy-Food (WEF) Nexus Tool 2.0, adapted to include the phosphate industry (WEF-P tool). It assesses the scenarios based on priorities identified by the Moroccan phosphate industry, such as the environmental impact of transporting phosphate rock by train and phosphate slurry by pipeline and increased desalinated water use. Results show that each scenario's sustainability can be assessed in terms of phosphate production, processes, resource (water and energy) availability, and CO2 emissions in mining and manufacturing areas. The analytical methodology of the tool is based on an integrated supply chain and life cycle assessment, which includes the production flows linking mining phosphate and manufacturing phosphorous fertilizers and their water and energy supply systems. Field surveys were used to identify the supply chain and estimate the relationships between production and resource consumption in each process. The tool is a decision-support platform that produces sustainability indices for multiple scenarios of resource allocation (water and energy) and CO2 emissions, allowing stakeholders to compare potential outcomes and formulate decisions based on their understanding of the actual trade-offs involved.

Ni2P Nanoparticle-Inserted Porous Layered NiO Hetero-Structured Nanosheets as a Durable Catalyst for the Electro-Oxidation of Urea.

The electro-oxidation of urea (EOU) is a remarkable but challenging sustainable technology, which largely needs a reduced electro-chemical potential, that demonstrates the ability to remove a notable harmful material from wastewater and/or transform the excretory product of humans into treasure. In this work, an Ni2P-nanoparticle-integrated porous nickel oxide (NiO) hetero-structured nanosheet (Ni2P@NiO/NiF) catalyst was synthesized through in situ acid etching and a gas-phase phosphating process. The as-synthesized Ni2P@NiO/NiF catalyst sample was then used to enhance the electro-oxidation reaction of urea with a higher urea oxidation response (50 mA cm−2 at 1.31 V vs. RHE) and low onset oxidation potential (1.31 V). The enhanced activity of the Ni2P@NiO/NiF catalyst was mainly attributed to effective electron transport after Ni2P nanoparticle insertion through a substantial improvement in active sites due to a larger electrochemical surface area, and a faster diffusion of ions occurred via the interactive sites at the interface of Ni2P and NiO; thus, the structural reliability was retained, which was further evidenced by the low charge transfer resistance. Further, the Ni2P nanoparticle insertion process into the NiO hetero-structured nanosheets effectively enabled a synergetic effect when compared to the counter of the Ni2P/NiF and NiO/NiF catalysts. Finally, we demonstrate that the as-synthesized Ni2P@NiO/NiF catalyst could be a promising electrode for the EOU in urea-rich wastewater and human urine samples for environmental safety management. Overall, the Ni2P@NiO/NiF catalyst electrode combines the advantages of the Ni2P catalyst, NiO nanosheet network, and NiF current collector for enhanced EOU performance, which is highly valuable in catalyst development for environmental safety applications.

Field and Economic Studies on Mine Waste: Sustainable Reuse as Aggregates for Low Traffic Pavement Structure

The phosphate extraction and processing has followed a traditional linear consumption model, where wastes are continuously produced and surface land is filled in rock piles. Thus, to promote a circular economy in a mining context, more eco-friendly and sustainable solutions at the regional level are needed. This paper deals with the potential utilization of phosphate screening waste rock 0–100 mm (SWR) as alternative aggregates for pavement applications. Detailed in situ and laboratory tests have been made for SWR characterization, and the practical modalities of implementation have been defined. The findings proved that SWR (10–100 mm) materials can be successfully used without treatment in capping layer construction for low-volume traffic pavement projects. Due to its high apatite content, the remaining fraction (0–10 mm) can be exploited to recover the residual phosphate using the processing method that is currently followed by the mining company. Furthermore, the environmental investigations showed that SWR does not present any potential contamination risk to the surrounding environment. The economic feasibility analysis confirmed the workability of SWR reuse in a radius of 100 km around their dumps due to its lower cost compared to conventional aggregates. This simple amendment may ensure a smooth transition from a current linear extractive approach to a circular economy.

Study of the Preparation of Micronized Zinc Phosphate Dihydrate with Potential for Application in the Phosphating Process

The protection of metal parts against corrosion damage is one of the most comprehensive areas of industrial chemistry and a wide range of methods exists to protect the surface from corrosive stimulators, including phosphating. A key phosphating process, the tricationic phosphating, consists of baths containing zinc dihydrogen phosphate and other cations, such as Zn2+, Co2+, Ni2+ or Mg2+. However, cobalt and nickel ions are classified as environmentally harmful and they are being actively excluded from industrial processes. The use of sufficiently micronized zinc phosphate dihydrate (µ-Zn3(PO2)2 · 2H2O) is one the possible approaches to significantly reduce or eliminate heavy metals from the phosphating process. The micronized zinc phosphate dihydrate serves as a nucleus on the metal surface to form a sufficiently high-quality phosphate layer. The study aims to find a procedurally optimal dispersion methodology suitable for application in the Czech Republic. The use of progressive grinding methods such as the jet mills is emphasized and shows promising results.

NiCoP/g-C3N4 Schottky heterojunctions towards efficient photocatalytic NO oxidation

NiCoP/g-C3N4 Schottky heterojunctions were created by a two-step synthesis for enhanced NO oxidation. NiCo-layered double hydroxides (LDH) were grown on superior thin graphic carbon nitride (g-C3N4) nanosheets by a controlling chemical co-precipitation method. A phosphating process at 300 °C resulted in the transformation in situ of NiCo-LDH into NiCoP composite nanoparticles to create Schottky heterojunctions. Using optimized conditions, heterojunction sample 15-NiCoP/CN revealed excellent photocatalytic NO oxidation with a removal rate of 78%. Photogenerated electrons were efficiently separated and transferred because of Schottky barrier, interfacial charge transport channel, and enhanced light absorption efficiency. Photogenerated electrons reacted with adsorbed O2 to generate superoxide radicals (·O2¯) as crucial active species of NO oxidation. The test indicated that the concentration of·O2¯ for sample 15-NiCoP/CN reached 7.1 × 10−5 M which was 6.5 times higher than that of g-C3N4 after light irradiation. In addition, low NO2 generation and mineralization rate (92%) suggested that NO was converted into NO3- or NO2- rather than NO2 to mitigate secondary pollution. This result supplied a novel approach to explore the application of transition metal phosphides and g-C3N4 in photocatalytic NO oxidation.

Hollow CoP microspheres as superior bifunctional electrocatalysts for hydrogen evolution in a broad pH range and oxygen evolution reactions

Morphology regulation and ion doping are two common ways to improve catalytic performance. Herein, hollow CoP microspheres were synthesized via a facile template-free solvothermal approach with a following low-temperature phosphating process. The as-synthesized CoP hollow microspheres show preeminent electrocatalytic HER performance in a wide pH range (1.0 ​M KOH, 1.0 ​M PBS and 0.5 ​M ​H2SO4), and also deliver superior OER catalytic activity and low Tafel slope. Meanwhile, its catalytic activity could be maintained almost unchanged for at least 6 ​h in acidic solution, neutral solution and alkaline solution. These superior electrochemical properties will render the hollow CoP microsphere material as an attractive material for promising application in high-performance electrochemical water decomposition systems.

Boosting electrocatalytic hydrogen evolution over the wide pH range for CoP3 nanowire arrays via Ni doping

CoP 3 is a promising electrocatalyst for the hydrogen evolution reaction, however it is still challenging for CoP 3 -based catalyst to deliver excellent activities in a wide pH range. In this work, the self-standing Ni-doped CoP 3 nanowire arrays (Ni-CoP 3 NWs) on carbon fiber paper were synthesized by hydrothermal method followed with an in situ phosphating process. The results show that the Ni doping effectively boosts the electrocatalytic hydrogen evolution for CoP 3 NWs over the wide pH range with good stability. The Ni doped CoP 3 NWs sample with the Ni: Co mole ratio of 10% (Ni-CoP 3 -10%) shows a low overpotential of 66 mV to afford the current density of 10 mA cm −2 in 0.5 M H 2 SO 4 , which is the optimal catalytic performance in this work. Furthermore, Ni-CoP 3 -10% sample also shows excellent electrocatalytic performance in alkaline and neutral conditions, which needs the overpotential of 114 and 131 mV to afford the current density of 10 mA cm −2 in 1 M KOH and 1 M PBS, respectively. The enhanced electrocatalytic activity can be ascribed to that the Ni doping improves the electron transport, increases the electrochemical active surface area and optimizes the Gibbs free energy of hydrogen adsorption for the CoP 3 NWs, which develops it as a promising electrochemical catalyst for hydrogen evolution. • Ni doped CoP 3 nanowire arrays are prepared by vacuum encapsulation technique. • Ni doping boosts the HER activity for CoP 3 in wide pH media. • The reasons of the enhanced HER performance for Ni doped CoP 3 is revealed.

Improving the Performance of Photocatalytic Hydrogen Production through Adjusting the Size of Defective Quantum Dots Co‐Catalyst Affected by Intramolecular Steric Hindrance on Thermal Stability of Functional Groups

Quantum dots (QDs) co‐catalysts have been extensively studied in the field of photocatalytic hydrogen production (PHP) due to their limited domain effect. However, how to adjust the size of QDs co‐catalysts remains a big challenge. Herein, Ni2P QDs co‐catalysts are synthesized via phosphating metal–organic frameworks (MOFs). Due to the intramolecular steric hindrance on the thermal stability of functional groups: electron‐giving functional groups ‐NH2, ‐OH, and electron‐absorbing functional group ‐COOH, the electronic symmetry of organic ligands and the coordination with metal ions is affected, resulting in three sizes of Ni2P QDs co‐catalysts in the phosphating process, and the smallest one has the highest interfacial charge injection efficiency and transfer rate. Meanwhile, the carbon defects of the carbon skeleton produced in the phosphating process, in which the band position is lower than the conduction band of the Zn0.5Cd0.5S (ZCS) catalyst, can effectively collect electrons and inhibit the recombination of photocarriers to a greater extent, and Ni defects adjust the internal electronic structure of Ni2P QDs. The results of experiments and density functional theory calculations demonstrate that Ni2P@ZCS has excellent electronic structure and electron transfer efficiency. Thus, the best PHP performance of Schottky junctions Ni2P@ZCS is achieved with the combined efforts of QDs co‐catalysts and defects.

Co(OH)F@CoP/CC core-shell nanoarrays for high-performance supercapacitors

The transition metal phosphides have drawn wide attention as positive material used in supercapacitors owing to the excellent conductivity and electrochemical activity. In this work, the novel composite Co(OH)F@CoP core-shell nanoarrays, used as electrode material for supercapacitors, was synthesized on conductive carbon cloth (CC) through the hydrothermal method and phosphating process. The specific capacitance of Co(OH)F@CoP/CC is 654mC cm−2 at 1 mA·cm−2, and maintains long-life cycling stability of 71.34 % retention after 10,000 cycles at 10 mA·cm−2 in a three electrode system. Furthermore, a two-electrode system assembled by Co(OH)F@CoP and reduced graphene oxide (RGO) exhibits performance with energy density of 17.933 Wh kg−1 at power density of 800 W kg−1. These results proved that the Co(OH)F@CoP composite is an advanced electrode material for the supercapacitors.

Cobalt-doping of molybdenum phosphide nanofibers for trapping-diffusion-conversion of lithium polysulfides towards high-rate and long-life lithium-sulfur batteries

Rational design of separators is especially critical to solve the “shuttle effect” of lithium polysulfides (LiPSs) and the sluggish redox kinetics in lithium-sulfur batteries (LSBs). Here, the multi-functional nanocomposite involving Co-doped molybdenum phosphide (Co-MoP) nanofibers and porous carbon nanofibers (PCNFs) is designed and prepared through electro-blow spinning and phosphating process, which possesses multiple adsorption and catalytic sites and is acted as the functional material for LSBs separators. In this multifunctional nanocomposite, the prepared Co-MoP nanofibers can provide internal adsorption and catalytic sites for LiPSs conversion. And the interconnected nitrogen-doped PCNFs can be elaborated an efficient LiPSs mediator and accommodate the huge volume changes in the reaction process for LSBs. Benefiting from the multiple adsorptive and catalytic sites of the developed functional materials, the assembled LSBs with a Co-MoP/PCNFs modified separator display outstanding electrochemical performances, including an admirable capacity retention of 770.4 mAh g−1 after 400 cycles at 1.0 C, only 0.08 % capacity decay per cycle at 2.0 C, rate performance up to 5 C, and also decent areal capacity even under a high sulfur loading of 4.9 mg cm−2. The work provides a facile pathway towards multifunctional separators in LSBs, and it may also help deepen preparation method of MoP through the electrostatic blowing/electrospinning technology in other related energy storage fields.

Preparation and anticorrosion properties of electrodeposited calcium phosphate (CaP) coatings on Mg–Zn–Ca metallic glass

In order to improve the corrosion resistance and bioactivity of Mg–Zn–Ca metallic glass, a series of calcium phosphate (CaP) coatings were synthesized on Mg66Zn30Ca4 metallic glass via the electrodeposition method in this paper. As compared with the Mg-based metallic glass, the electrodeposited CaP coatings show considerable improvement in corrosion resistance and bioactivity. Based on the experimental results, the formation and anti-corrosion mechanisms of CaP coatings were proposed, suggesting that electrodeposited CaP coating can promote the precipitation of calcium phosphate and thereby induce the mineralization process. By constructing the predominance area diagram, the relationship between the composition of the CaP solution and the precipitation process of calcium phosphate (CaHPO4·2H2O, Ca5(PO4)3OH) at 25 °C was accurately described. These results provide insights into the electrodeposition process of CaP type coatings.

The influence of silicon on the formation of phosphate coatings for low-carbon IF steels

It is essential to clarify the influence of silicon on the phosphating process for low-carbon IF steels. In the present work, the formation of phosphate coatings for the IF steels with 0.01 wt%, 0.1 wt% and 0.5 wt% silicon was experimental determined by the combination of electrochemical characterization with X-rays photoelectron spectroscopy (XPS), focused Ion beam and transmission electron microscope (FIB-TEM), X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. It was confirmed that the silicon layer formed on the IF steels surface was mainly composed by Si, SiO2, SiC, Si3+ and oxides of Fe. Thicker silicon layers were formed with the increase of silicon concentrations, which inhibited the electrochemical reaction on the steels surface during the phosphating process. The diffusion of the ions including Me2+, PO43− and H+ to the surface of the substrate was severely restricted by the thick silicon layer, leading to the deterioration of the phosphating performance. The influence mechanism of silicon was finally proposed for a deep understanding of the phosphating process for IF steels.

Regeneration Process of Ammonia-Absorbed Zirconium Phosphate to Zirconium Phosphate

Zirconium phosphate [Zr(HPO4)2·H2O] absorbs 2 mol(NH3)/mol[Zr(HPO4)2·H2O] with a low equilibrium plateau ammonia concentration of around 1 ppm in water. In this study, in order to investigate the regeneration process of ammonia-absorbed zirconium phosphate [Zr(NH4PO4)2·H2O], Zr(NH4PO4)2·H2O was heat-treated above 353 K under an inert gas. Then, the structures of the heat-treated samples were evaluated using powder X-ray diffraction and thermogravimetry–mass spectrometry measurements. Zr(NH4PO4)2·H2O started to desorb ammonia and the crystal water at 353 K. Then, Zr(NH4PO4)2·H2O was changed to the anhydrous monoammoniate [Zr(NH4PO4)(HPO4)] at 473 K and formed anhydrous zirconium phosphate [Zr(HPO4)2] at 673 K. The anhydrous zirconium phosphate and the anhydrous monoammoniate reabsorbed ammonia in ammonia water. Those initial absorption rates were small compared with Zr(HPO4)2·H2O. The slow kinetics of the anhydrous zirconium phosphate corresponded to the small interlayer distances. The ammonia concentration composition isotherms indicated that the anhydrous zirconium phosphate and anhydrous monoammoniate have a low ammonia equilibrium plateau concentration of around 1 ppm in ammonia water. Zr(NH4PO4)2·H2O is formed from Zr(NH4PO4)(HPO4) by the reabsorption of ammonia and water after 1–10 cycles. We found that zirconium phosphate is an ammonia remover which can be used repeatedly at 473 K.

Mass transfer study and combined model for a Karr column

• Drop size and concentration profiles were measured in a Karr column. • A combined model considered flow non-ideality in both phases. • Model was applied and compared with columns with different diameters. Mass transfer performance of a Karr reciprocating plate column was studied with water (continuous) - phenol (solute) - VivaSol 2046 + 10v% tributyl phosphate (dispersed), for both extraction and stripping processes. Drop size distribution and concentration profiles along the column height were measured experimentally. A combined model accounted for flow non-ideality in both phases. A backflow model to describe backmixing for the continuous phase and a population balance model to consider the forward mixing for the dispersed phase was applied. The model was in good agreement with the experimental data and was applied to various flow rates. A concentration jump was observed at the continuous phase inlet when backmixing was obvious while no jump at dispersed phase inlet. The combined model provided better predictions comparing with the backflow model for both phases. Finally, the model was validated and compared with the measured Sauter mean diameter and concentrations for Karr columns with different diameters.

Rice straw derived adsorbent for fast and efficient phosphate elimination from aqueous solution

Rice straw (RS) is an abundant agricultural residue with plentiful hydroxyl groups. In this study, a low-cost and effective RS-based phosphate adsorbent (RS-PA) was prepared through a three-step reaction process, successively with epichlorohydrin (ECH), ethylenediamine (EDA), and triethylamine (TEA). The elimination process of phosphate was optimized by considering altered adsorption conditions. The successful production of RS-PA was confirmed by FTIR, organic element, and zeta potential analyses. The key factors influencing the phosphate adsorption were the temperature in the second reaction step and EDA dosage. Langmuir isotherm and pseudo-second-order kinetic models predicted the phosphate adsorption on the RS-PA very well. A complete phosphate removal was achieved at 50 mg/L phosphate concentration, 10 g/L adsorbent dosage and 25 ℃ in 10 min. The exothermic nature of phosphate adsorption on RS-PA was confirmed since the temperature rise reduced the adsorption of phosphate on the adsorbent. These results demonstrate that full component rice straw-based phosphate adsorbent was successfully prepared for the removal of phosphorus compounds from waste water.

Gap channel carbon layer coated bimetallic CoFe phosphate as a bifunctional electrocatalyst for overall water splitting

Designing efficient non-precious electrocatalysts to facilitate overall water splitting is crucial and highly desirable, but remains challenging. Herein, a carbon-coated bimetallic CoFe phosphate (Co7Fe3–P/C) electrocatalyst is synthesized via simple gel-sol, pyrolysis and phosphating process. Co7Fe3–P/C exhibits excellent activity with low overpotential of 194 and 260 mV to achieve a current density of 10 mA cm−2 in alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. With Co7Fe3–P/C as two-electrode for overall water splitting, only a low cell voltage of 1.76 V and 1.88 V is required to achieve a current density of 100 mA cm−2 and 500 mA cm−2, which outperform that of the commercial Pt/C–RuO2 couple and reported CoFe alloy materials, showing the promising potential application in the industrial water electrolysis. The superior activity of overall water splitting over carbon-coated bimetallic CoFe phosphate electrocatalyst is attributed to the excellent mass transfer by gap channel of carbon layer, charge enhancement effect by phosphating and in-situ oxidization into its corresponding amorphous (oxy)hydroxides (CoOOH and FeOOH).

Effect of Polyimide-Phosphating Double Coating and Annealing on the Magnetic Properties of Fe-Si-Cr SMCs.

Fe-Si-Cr soft magnetic powder cores (SMCs), with high electrical resistivity, magnetic permeability, saturation magnetic induction, and good corrosion resistance, are widely applied to inductors, filters, choke coils, etc. However, with the development of electronic technology with high frequency and high power density, the relative decline in the magnetic properties limits the high-frequency application of SMCs. In this paper, the phosphating process and polyimide (PI) insulation coating is applied to Fe-Si-Cr SMCs to reduce the core loss, including hysteresis loss and eddy current loss. The microstructure and composition of Fe-Si-Cr powders were analyzed by SEM, XRD, and Fourier-transform infrared spectra, respectively. The structural characteristics of the Fe-Si-Cr @ phosphate layer @ PI layer core–shell double coating were studied, and the best process parameters were determined through experiments. For SMCs with 0.4 wt% content of PI, the relative permeability is greater than 68%, and the core loss is the lowest, 7086 mW/cm3; annealed at 500 °C, the relative permeability is greater than 57%, and the core loss is the lowest, 6222 mW/cm3. A 0.4 wt% content of PI, annealed at 500 °C, exhibits the ideal magnetic properties: μe = 47 H/m, P = 6222 mW/cm3.

Intermodel comparison for the radiological assessment of the Zapadnoe and Tessenderlo case studies with implications for selection of remediation strategy

Risk assessment provides a key input for determining the need for and extent of remedial actions necessary for sites contaminated with naturally occurring radioactive material or nuclear legacy sites. The choice of a modelling approach for risk assessment, and the corresponding toolsets should fit the assessment context, taking account of the complexity, and be clearly related to the questions to be addressed in the decision-making process. One of the objectives of Working Group 1 of IAEA Modelling and Data for Radiological Impact Assessments II (MODARIA II) Programme is to perform intermodel comparisons for case studies of selected sites, in particular, to help illustrate the applicability of different models and approaches as inputs to decision-making processes. This intercomparison exercise, which included the analysis of potential consequences on the management strategy for contaminated sites, has been performed for two sites: The former uranium mill tailings facility at Zapadnoe, Ukraine, and the phosphate processing facility at Tessenderlo, Belgium. Several models and computer codes have been used for one or both of these cases: AMBER, GoldSim, NORM And LegacY Site Assessment, Preliminary Remediation Goals (PRG)-dose compliance concentration calculator, and RESRAD-OFFSITE. The assessments explore the implications of using differing assessment frameworks and assumptions, as well as alternative modelling tools, on model outputs and as input for corresponding decisions on remediation strategy. This paper reviews both similarities and differences in the results of assessments performed using these different models. It discusses how different approaches can complement one another to help build confidence in the evidence base underpinning decisions. It also discusses the appropriateness of the different modelling approaches in a given assessment context. In one of the case studies in particular (Tessenderlo case study), the remediation strategy is essentially driven by the contamination of the site with heavy metals, such as cadmium. This has significant consequences on the choice of the most adequate approaches and scenarios for assessing the radiological risk and balancing their relative importance with other impacts. The development of a holistic approach to risk assessment is, therefore, highlighted.

Superhydrophilic/Superaerophobic Hierarchical NiP2@MoO2/Co(Ni)MoO4 Core–Shell Array Electrocatalysts for Efficient Hydrogen Production at Large Current Densities

Rationally constructing low-cost, high-efficiency, and durable electrocatalysts toward the hydrogen evolution reaction at large current densities is imperative for water splitting, especially for large-scale industrial applications. Herein, a hierarchical core-shell NiP2@MoO2/Co(Ni)MoO4 cuboid array electrode with superhydrophilic/superaerophobic properties is successfully fabricated and the formation mechanism of the core-shell structure is systematically investigated. Through an in situ partially converted gas-solid reaction during the phosphating process, Ni and Co elements are leached and rearranged to form NiP2 particles and amorphous CoO as the shell layer and the inner undecomposed Co(Ni)MoO4 crystals serve as the core layer. Because of its seamless core-shell structure and superhydrophilicity/superaerophobicity of hierarchical cuboid arrays, NiP2@MoO2/Co(Ni)MoO4 exhibits superior HER activity in 1 M KOH with only an overpotential of 297 mV to deliver 1000 mA cm-2 and can work steadily for 650 h at 200 mA cm-2. Remarkably, when coupled with NiFe LDH for overall water splitting, it can drive an AA battery with an ultralow cell voltage of 1.49 V to deliver 10 mA cm-2. This work sheds new light on designing large-current-density efficient HER electrocatalysts for large-scale industrial applications.