Tuning oxygen evolution activity via transition metal doping in bimetallic nickel phosphates

Abstract The electrochemical nitrate reduction reaction (NO 3 − RR) presents a promising strategy for simultaneous wastewater remediation and ammonia synthesis. However, the fabrication of efficient, stable, and economically viable electrocatalysts remains a significant challenge. Addressing this, we report the rapid (14 min) electrodeposition of an amorphous nickel phosphate catalyst directly onto a metallic foam cathode, utilizing nickel plating wastewater as a precursor under high‐current conditions. This catalyst exhibits exceptional performance in acidic media, achieving a Faradaic efficiency of 96.6% for ammonia at −0.5 V (versus RHE) in 10 mM NO 3 − solution, alongside remarkable electrochemical stability exceeding 20 h. We attribute the catalyst formation to the oxidation of hypophosphite at the cathode interface during high current polarization and its subsequent co‐deposition with Ni 2+ ions. When applied to actual nickel plating wastewater at 200 mA cm −2 , the system demonstrated relatively stable operation for 30 h and successfully recovered ammonium sulfate. Combined experimental and theoretical analyses reveal the origin of the superior NO 3 − RR activity. This work provides an innovative waste‐derived strategy for the rapid synthesis of high‐performance catalysts and advances the sustainable recovery of nitrogen, phosphorus, and nickel from industrial waste streams.

The electrochemical nitrate reduction reaction (NO3 -RR) presents a promising strategy for simultaneous wastewater remediation and ammonia synthesis. However, the fabrication of efficient, stable, and economically viable electrocatalysts remains a significant challenge. Addressing this, we report the rapid (14min) electrodeposition of an amorphous nickel phosphate catalyst directly onto a metallic foam cathode, utilizing nickel plating wastewater as a precursor under high-current conditions. This catalyst exhibits exceptional performance in acidic media, achieving a Faradaic efficiency of 96.6% for ammonia at -0.5V (versus RHE) in 10mM NO3 - solution, alongside remarkable electrochemical stability exceeding 20 h. We attribute the catalyst formation to the oxidation of hypophosphite at the cathode interface during high current polarization and its subsequent co-deposition with Ni2+ ions. When applied to actual nickel plating wastewater at 200mAcm-2, the system demonstrated relatively stable operation for 30 h and successfully recovered ammonium sulfate. Combined experimental and theoretical analyses reveal the origin of the superior NO3 -RR activity. This work provides an innovative waste-derived strategy for the rapid synthesis of high-performance catalysts and advances the sustainable recovery of nitrogen, phosphorus, and nickel from industrial waste streams.

In situ upgrading of heavy crude oil (10.0 °API) was carried out via catalytic aquathermolysis using a nickel-based catalyst impregnated onto a limestone rock matrix at 300 °C and 300 psi for 72 h. The catalyst was effectively retained within the rock matrix and self-activated under reaction conditions, leading to the formation of catalytically active crystalline phases, such as nickel phosphate ([Ni3(PO4)2]) and nickel sulfide (NiS), as confirmed by X-ray diffraction and X-ray fluorescence analyses. Unlike previous catalytic aquathermolysis reports that mainly describe soluble or transient catalytic species, this study demonstrates for the first time the in situ generation and stabilization of these active nickel phases within a carbonate matrix, providing long-term catalytic activity under reservoir-relevant conditions. Importantly, the limestone matrix facilitated catalyst retention and promoted the in situ generation of active nickel phases, thereby creating synergistic sites that markedly enhanced the efficiency of the catalytic aquathermolysis process. Compared to the pristine heavy crude oil, the upgraded oil exhibited improved properties by reducing the viscosity by 44%, increasing API gravity by 4 units, and enhancing the gasoline and diesel fractions by 54 and 44%, respectively, primarily at the expense of the residue content, which decreased from 66.4 to 45.5%. GC-simulated distillation analysis of the upgraded oil revealed a notable reduction in molecular weight, attributed to the catalytic upgrading process through hydrocracking reactions of heavy hydrocarbons. Gas chromatography of the evolved gases revealed the presence of hydrogen, methane, and hydrogen sulfide, serving as indirect evidence of the catalytic aquathermolysis process. These light compounds were generated through the thermal and catalytic cleavage of C-S and C-C bonds in heavy crude oil molecules, with reaction rates enhanced by the presence of the catalyst. The fed water molecules participated in hydrogen transfer, hydrocracking, and desulfurization reactions. It was also deduced that the interaction between the catalyst and the limestone matrix provided additional active sites, ultimately eliminating the need for external hydrogen sources. These findings demonstrate the potential of in situ catalytic aquathermolysis as a transformative technology for upgrading heavy crude oil, enhancing both its recovery and quality, and paving the way for field-scale applications.

Nickel Phosphate (NiP) has been successfully synthesized through the precipitation method. The effect of pH, stirring temperature, and Ni:P molar ratio on NiP formation has been studied. The optimization showed that NiP is formed at pH 6, stirring temperature of 90 °C, and a molar ratio of Ni:P of 3:6. Then, the obtained powder was calcined at a temperature of 350-800 °C. The synthesised NiP was characterized using X-ray powder diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, nitrogen adsorption-desorption, and Scanning Electron Microscopy (SEM). The characterization results showed that the NiP structure was amorphous at 350-600 °C and transformed into a monoclinic crystalline of Ni₃(PO₄)₂ at 800 °C. Nitrogen adsorption isotherms showed that the NiP result had a predominance of micropores with little mesoporous contribution. Sample NiP_350 shows the highest surface area (9.94 m2/g) with a more uniform pore distribution. FTIR-pyridine analysis identified the existence of both Lewis and Brønsted acid sites, with the predominance of Brønsted acid at low calcination temperatures. The increase in calcination temperature resulted in reduced surface area and total acidity due to pore coalescence and dehydration, which was in line with the results of SEM, which showed a denser morphology. Overall, these results confirm that variations in synthesis and calcination conditions play an important role in determining the textural properties, acidity, and structure of NiP, which makes them potential candidates for catalysis and adsorption applications.

In this study, we report a novel and practical tandem approach for synthesizing symmetric ketazines derived from the reaction of hydrazine hydrate and Acetophenone using nickel phosphate (NiP) as a heterogeneous nano-catalyst for the first time. The catalyst underwent comprehensive characterization using several techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Ultraviolet-visible Spectroscopy (UV-Vis), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDS), X-ray diffraction (XRD), and N2 adsorption-desorption isotherm using BET and BJH methods to define their structure and properties. The results demonstrate that the catalyst exhibited a high surface area of 266.10 m2/g and a heterogeneous nano- structure with high stability and reusability. The synthesized ketazines were analysed using Infrared Spectroscopy (IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. Additionally, the fluorescence properties of the ketazines were tested under various conditions, such as different concentrations and solvents. Also, the same molecules were used in the detection of Fe2+ and Pb2+ ions in water. Notably, significant alterations in the fluorescence properties were observed.

Cost-effective assembly of high-performance yumberry-like nickel phosphate aggregates for high-energy density hybrid supercapacitors

Impact of BaO on structural, optical, and radiation shielding characteristics of barium nickel phosphate glasses

Facing the fossil energy crisis and environmental issues, developing renewable energy is urgent, with green hydrogen being crucial in energy transition but electrolytic water hydrogen production has high costs needing solutions, such as replacing oxygen evolution reaction (OER) with organic oxidation reactions. Here, Co-doped amorphous nickel phosphate materials (Co-NiPxOy/NF) are synthesized via electrodeposition and applied as catalysts for the methanol oxidation reaction (MOR). The 10% Co-doped material demonstrates remarkable efficacy in catalyzing MOR. When compared to the OER, it reduced the applied potential required to reach a current density of 200 mA cm⁻2 by 227 mV. During constant-current electrolysis at current densities ranging from 20 to 250 mA cm⁻2, the Faraday efficiencies (FE) of the formate products consistently exceeded 90%, and the catalysts maintained stable electrolysis for 120 h. into and discussed the action mechanism of Co-NiPxOy/NF is delved, proposing a dual-mechanism model involving hydrogen vacancy oxygen and electrophilic OH* species. These findings provide a solid theoretical foundation for the rational design and modification of catalysts, thereby paving the way for the development of a more efficient and cost-effective electrolytic water-based hydrogen production technology.

Abstract The escalating demand for renewable and sustainable energy underscores the critical need for efficient and cost‐effective catalysts for hydrogen and oxygen evolution reactions (HER and OER) in water splitting. Nickel phosphates (NiPOs) have garnered significant attention as promising bifunctional electrocatalysts, owing to their abundance, low cost, and superior catalytic properties. In this study, NiPO nanoparticles were synthesized using a hydrothermal method followed by air annealing, presenting a scalable and environmentally benign approach. The optimized NiPO catalyst exhibited outstanding electrochemical performance, achieving HER at an overpotential of 256 mV and OER at 320 mV at a current density of 10 mAcm−2 in a 1 M KOH electrolyte. The enhanced catalytic activity was attributed to the unique electronic structure of NiPO, which facilitates increased active site availability and robust ionic and metallic bonding (Ni─P). Furthermore, the catalyst demonstrated excellent durability, maintaining stable performance over 20 h of continuous operation. Beyond electrochemical metrics, the practical applicability of NiPO was validated by its impressive gas evolution rates, producing 0.632 mmol g−1 h−1 of H₂ and 0.280 mmol g−1 h−1 of O₂. These results underscore the potential of air‐annealed NiPO as a cost‐effective and durable bifunctional catalyst for water splitting, advancing sustainable hydrogen energy production and paving the way for real‐world implementation in renewable energy technologies.

This study presents a comprehensive investigation of the oxygen evolution reaction (OER) activity on nickel phosphate (NiPO) surfaces doped with transition metals (Mn, Fe, Co, and Cu). By combining density functional theory calculations, the computational hydrogen electrode approximation, and microkinetic simulations, we demonstrate that transition metal doping significantly enhances OER performance compared to the pristine NiPO surface. The observed trends in overpotential values align with the oxygen adsorption energies on the doped surfaces, indicating a consistent improvement in catalytic activity. Despite the incorporation of different transition metals, the electronic profiles of surface nickel atoms remain largely unchanged, resulting in similar overpotential values at these sites. This suggests that the enhanced OER activity is primarily driven by the localized electronic states of the embedded transition metal dopants rather than changes in the nickel sites. Among the dopants studied, Fe and Mn exhibit the best OER performance, followed by Co and Cu.

Optimized Nickel Phosphate Cocatalyst on Ge-Doped Hematite Photoanode for Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid

Binder-free chemical synthesis of stacked nickel phosphate hydrate faceted micropetals for urea electrocatalysis

Abstract Ni–P electroless coatings are widely utilized in industrial applications due to their exceptional hardness and wear resistance. To enhance the wear resistance of Ni–P coatings and reduce the wear of counterparts, a Ni–P-MSH composite coating was fabricated successfully through the incorporation of environmentally friendly magnesium silicate hydroxide (MSH) nanoparticles. This study demonstrates that MSH significantly influences the hardness, crystal structure, and chemical composition of the Ni–P coating, offering a novel approach to performance enhancement. Results show that the wear-rate of Ni–P-MSH1 composite coating decreases by about 82.9% compared with the Ni–P coating, with its wear resistance comparable to that of the heat-treated Ni–P-AT300 coating with high hardness. Furthermore, the steel ball sliding against the Ni–P-MSH1 coating exhibited a wear-rate three orders of magnitude lower than that observed with the Ni–P-AT300 coating, highlighting the excellent lubrication performance of the Ni–P-MSH1 coating. The outstanding wear resistance of Ni–P-MSH composite coatings can be attributed to the formation of a tribofilm composed of nickel oxide and phosphate on the surface of the coatings, and this discovery lays a foundation for the development of high-performance and eco-friendly coating materials.

The construction of an efficient and durable oxygen evolution reaction (OER) electrocatalyst through a simple synthesis strategy is crucial for the hydrogen produced from seawater splitting. However, achieving this goal remains a great challenge. Herein, the synthesis of amorphous Fe-doped nickel phosphate (Fe-NixPO4) as a high-performance OER electrocatalysts for alkaline freshwater/seawater splitting is presented using a straightforward co-precipitation method at room-temperature. Experimental results reveal the structural reconstruction of Fe-NixPO4 into Fe-doped NiOOH decorated with PO4 3-. The collaborative interplay between Ni2+ and Fe3+, along with the decoration of PO4 3-, can effectively modulate the electronic environment of the electrocatalyst. Consequently, the optimized Fe-NixPO4 exhibits exceptional OER activity, requiring overpotentials of 359 and 422mV to generate 1000mA cm-2 in alkaline freshwater and alkaline seawater, respectively. Moreover, Fe-NixPO4 also displays outstanding stability for 100h at 100mA cm-2 in alkaline seawater. This research presents a viable approach for fabricating OER electrocatalysts with exceptional efficiency for seawater electrolysis.

Abstract With the increasing scarcity of resources such as oil, research, and development of new energy has become an urgent task. In the use of new energy, there is a need to use various catalysts. The synthesis of transition metal nickel phosphate is the theme. By adding different molar ratios of sodium chloride, different concentrations of chloride ions can be introduced, making different mirror exposure ratios of nickel phosphate. Its structure is characterized by X-ray diffraction and Transmission electron microscope. The results of experiments show that distinct crystal surfaces of the produced nickel phosphorine catalysts have different specific surface areas and uniform dispersion of nanoparticles. According to our experiments and analysis, when sodium chloride is gradually added to proper proportion, Ni2P gradually decreases in the sample, and the Ni12P5 content also increases further. Subsequent research revealed that the catalyst’s structure and characteristics are significantly influenced by the synthesis circumstances and that optimal synthesis conditions can significantly raise the catalytic activity and stability. Encouraging the research and growth of linked subjects is undoubtedly important.

Evaluation of the optical properties and radiation shielding effectiveness of barium-containing nickel phosphate borosilicate glasses

Sol–gel synthesis of magnesium-doped lithium cobalt, nickel, and zinc olivine phosphates, and their electrochemical application

Oil bath approach of nickel phosphate (Ni3 (PO4)2) nanocrystal and their structural and functional properties

This work is focused on the synthesis and performance of Ni3(PO4)2-based catalysts doped with Cu, Co, Mn, Ce, Zr, and Mg for the complete oxidation of ethanol, aiming at reducing emissions from ethanol-blended gasoline. Nickel phosphate was prepared via the co-precipitation method, followed by impregnation with the specified dopants. The catalysts were thoroughly characterized by XRD, N2-physisorption, XRF, FTIR and Raman spectroscopy, FESEM, NH3-TPD, CO2-TPD, and H2-TPR to explain their performance. All catalysts achieved complete ethanol conversion (100%) at a temperature below 320°C. The performance of the catalysts was strongly influenced by the dopant type of which Co, Ce, Mn, and Mg showed high CO2 selectivity (selectivity > 90% at 95% ethanol conversion temperature (T95)). The mechanism of oxidation is affected by the acido-basicity of the catalysts and the redox properties leading to a reaction through ethylene formation over the acid catalysts and acetaldehyde over the basic catalysts. The redox properties of the doped catalysts play a crucial role in enhancing the catalytic activity and selectivity toward CO₂, as the redox-active dopants facilitate the activation of oxygen species, which are essential for the complete oxidation of ethanol. In particular, Co and Ce demonstrated superior redox characteristics, facilitating the conversion of intermediate species and leading to higher CO2 selectivity while minimizing undesirable by-products.