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Water splitting technology is an efficient approach to produce hydrogen (H2) as an energy carrier, which can address the problems of environmental deterioration and energy shortage well, as well as establishment of a clean and sustainable hydrogen economy powered by renewable energy sources due to the green reaction of H2 with O2. The efficiency of H2 production by water splitting technology is intimately related with the reactions on the electrode. Nowadays, the efficient electrocatalysts in water splitting reactions are the precious metal-based materials, i.e., Pt/C, RuO2, and IrO2. Ni (Co, Fe)-based layered double hydroxides (LDH) two-dimensional (2D) materials are the typical non-precious metal-based materials in water splitting with their advantages including low cost, excellent electrocatalytic performance, and simple preparation methods. They exhibit great potential for the substitution of precious metal-based materials. This review summarizes the recent progress of Ni (Co, Fe)-based LDH 2D materials for water splitting, and mainly focuses on discussing and analyzing the different strategies for modifying LDH materials towards high electrocatalytic performance. We also discuss recent achievements, including their electronic structure, electrocatalytic performance, catalytic center, preparation process, and catalytic mechanism. Furthermore, the characterization progress in revealing the electronic structure and catalytic mechanism of LDH is highlighted in this review. Finally, we put forward some future perspectives relating to design and explore advanced LDH catalysts in water splitting.

An electrochemical sensor is described for the simultaneous voltammetric determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). An indium-tin oxide (ITO) electrode was modified with a hierarchical core−shell metal-organic framework and Ag-doped mesoporous metal-oxide based hybrid nanocomposites on g-C 3 N 4 nanosheets. The morphology, structural and chemical composition of the hybrid nanocomposite was characterized using different analytical methods. The modified ITO showed superior electrocatalytic performance towards the oxidation of AA, DA and UA due to the enhanced surface area, synergistic effects and well-organized porous assembly. Figures of merit, include (a) linear responses from 0.1 to 200 μM, 2.5 to 100 μM and 2.5 to 625 μM; (b) detection limits (at S/ N  = 3) of 0.02, 0.01 and 0.06 μM, and (c) well separated oxidation peaks near −50, 186 and 390 mV (vs. Ag/AgCl) for simultaneous sensing AA, DA and UA, respectively. The sensor was evaluated by analysing spiked serum samples and gave data with precision, with recoveries of >98%. Graphical abstract Schematic Representation of a Mesoporous Silver-doped TiO 2 -SnO 2 Nanocomposite (h-ATS) on g-C 3 N 4 Nanosheets and Decorated with a Hierarchical Core−Shell Metal-Organic Framework (NC@GC) Based Electrochemical Sensor for Simultaneous Voltammetric Detection of Ascorbic acid, Dopamine and Uric acid

In direct alcohol fuel cells (DAFCs), energy conversion co‐occurs at the anode (alcohol oxidation reaction [AOR]) and cathode (oxygen reduction reaction [ORR]). The sluggishness of AOR and ORR needs highly electrocatalytically active and stable electrocatalysts that boost electrokinetics, which is central in electrocatalysts’ architectural design and modulation. This design entails enhanced engineering synthesis protocols, heteroatomic doping, metallic doping/alloying, and deliberate introduction of defective motifs within the electrocatalyst matrix. The electrocatalyst activity and behavior depend on the electrocatalysts’ nature, type, composition, and reaction media, acidic or alkaline. Alkaline media permits cheap nonplatinum group metals. This review elucidates the roles and electrocatalytic pathways on different AOR and ORR electrocatalysts and outlines the aspects distinguishing ORR in alkaline and acidic media. It gives up‐to‐date and ultramodern strategies, protocols, and underlying mechanisms pointing to the efficacy and efficiency of electrocatalysts. The focus centers on heteroatomic, metallic dopants, defects effects correlated to electrocatalytic properties and experimental and theoretical findings. For the advancement in the field, the present study discusses critical parameters for improving the performances of electrocatalysts for DAFCs and breakthroughs on the horizon. Conclusively, knowledge gaps and prospects of these materials for industrial viability and reigning futuristic research directions are presented. Electrochemical performance in direct alcohol fuel cells (DAFCs) is influenced by several factors, including deliberately inducing defects (heteroatomic and metallic dopants, defects, dislocations) on electrocatalysts using different engineering methods, and governs electrocatalytic pathways for the oxygen reduction and alcohol oxidation, and the ultimate improvement of DAFCs reactions is fundamental to the industrialization of fuel cell technology.

The yarn ball-like NiCo-LDH was electrodeposited on carbon paper (CP) through adjusting and controlling the synthetic parameters such as cobalt ion concentration, synthetic potential and time by potentiostatic deposition, and was constructed an enzyme-free glucose sensor; the electrocatalytic behavior of the as-prepared NiCo-LDH/CP electrode towards the glucose was investigated through cyclic voltammetry (CV) and amperometric current–time response (I-t). The results showed that the sensor constructed on the basis of as-prepared NiCo-LDH/CP had not only a wide range of 0.84–11.04 mM, high sensitivity (5810 μA·mM −1 ·cm −2 ) and a low detection limit of 0.0546 μM, but also remarkable selectivity, striking repeatability and stability. Besides, the sensor based on NiCo-LDH/CP electrode had an excellent actual measurement with the recoveries of 98.86–101.05%.

Since pentlandites are among the most promising catalysts for hydrogen evolution reactions (HER), in this study, we investigated the influence of different cobalt, iron, and nickel substitutions in the cationic sublattice and the form of the material (powder, ingot, sintered pellet) on catalytic performance. This complements previous results regarding a multi-component approach in these chalcogenides. It was shown that in the case of sulfur-rich pentlandites with a non-equimolar ratio of Co, Fe, and Ni, the impact of intrinsic material properties is smaller than the surface-related effects. Among powder forms, catalysts based on a combination of Fe and Co perform the best. However, in volumetric forms, extremely high contents of individual metals are favorable, albeit they are associated with active precipitations of foreign phases. The presence of these phases positively affects the recorded currents but slows down the reaction kinetics. These findings shed light on the nuanced interplay between material composition, form, and HER properties, offering insights for tailored catalyst design.

In this study, the synergistic tuning mechanism of heat treatment (600, 800, and 1000 °C) and dealloying (40, 60, and 80 °C) on the microstructure and electrocatalytic performance of an FCC + BCC-type CoCrNi0.5Ti0.3V0.2Al0.4 eutectic high-entropy alloy (EHEA) was systematically investigated. The findings indicate that with an increase in heat treatment temperature, there is a gradual increase in grain size and a change in the fraction of the two phases. Notably, heat treatment at 800 °C resulted in an FCC-dominated dual-phase structure with uniformly refined grains. As the dealloying temperature increased, the pore size also increased, leading to a uniform distribution of the internal FCC and BCC phases. The sample subjected to heat treatment at 800 °C and dealloying at 80 °C exhibited an OER overpotential of only 265 mV and a Tafel slope of 67.84 mV/dec, significantly enhancing the electrocatalytic activity and stability of the alloy. This study elucidates the mechanism by which the combination of heat treatment and dealloying processes optimizes the electrocatalytic performance of eutectic high-entropy alloys, providing a novel strategy for the design of non-precious metal electrocatalysts.

Fuel cell is considered the best candidate power source because of its high energy conversion rate, large capacity, and zero emission. However, noble metal catalysts as a key core material have some problems, such as high cost and poor durability. Therefore, in this paper, the active self-supporting nanoporous Pd–Ag catalysts are successfully formed by cryogenic treatment and one-step dealloying treatment of Al-Pd–Ag ribbons. The surface of the catalyst ligaments shows a certain degree of preferred orientation for high-index facets (220) and (311). The results show that the activity and stability of the catalysts for methanol electrocatalytic oxidation are significantly improved under the synergistic effect of special configuration and promoter Ag. The electrocatalytic activity of the catalysts is about 9.7 and 15.2 times that of commercial Pt/C and commercial Pd/C catalysts, respectively. After 5000 s, the current density of the 1800 rpm-deep2 sample is 382.88 mA·mg −1 , which is about 14.1 times and 39.9 times that of commercial Pt/C catalyst and commercial Pd/C catalyst.

Electrocatalysts play key roles in improving the performance of lithium sulfur (Li‐S) batteries. Here, the electrocatalytic activity of different CoSe2 surfaces for the polysulfide redox reactions in Li‐S batteries, by means of first‐principle calculations is considered. The authors demonstrate that there are obvious differences in surface energy (0.7–2.34 J m−2), adsorption energy for lithium polysulfides (LiPSs) (1.2–3.5 eV), Gibbs free energy of sulfur reduction reaction (SRR) (0.37–1.16 eV), and Li2S decomposition barrier (0.15–0.94 eV) among different CoSe2 surfaces, and thus lead to the different electrocatalytic activity for different CoSe2 surface. The stoichiometric CoSe2 surface with high surface energy, such as the (001) surface, tends to have stronger adsorption energy and larger SRR Gibbs free energy for LiPSs. The surface electron states are mainly dominated by p–d hybridization orbitals and the p‐band center is vital for the surface electrocatalytic properties. Such surface‐dependent mechanism may shed light on the design of sulfur host materials for high‐performance Li‐S batteries. Density functional theory is a powerful tool for theoretically designing and understanding lithium‐sulfur battery materials on an atomic scale. The different catalytic activities caused by the surface effects are very charming. The surface‐dependent electrocatalytic effect of the sulfur reduction reaction of CoSe2 may shed light on the design of sulfur host materials for high‐performance lithium‐sulfur batteries.

Pt-based magnetic nanocatalysts are one of the most suitable candidates for electrocatalytic materials due to their high electrochemistry activity and retrievability. Unfortunately, the inferior durability prevents them from being scaled-up, limiting their commercial applications. Herein, an antiferromagnetic element Mn was introduced into PtCo nanostructured alloy to synthesize uniform Mn-PtCo truncated octahedral nanoparticles (TONPs) by one-pot method. Our results show that Mn can tune the blocking temperature of Mn-PtCo TONPs due to its antiferromagnetism. At low temperatures, Mn-PtCo TONPs are ferromagnetic, and the coercivity increases gradually with increasing Mn contents. At room temperature, the Mn-PtCo TONPs display superparamagnetic behavior, which is greatly helpful for industrial recycling. Mn doping can not only modify the electronic structure of PtCo TONPs but also enhance electrocatalytic performance for methanol oxidation reaction. The maximum specific activity of Mn-PtCo-3 reaches 8.1 A·m -2 , 3.6 times of commercial Pt/C (2.2 A·m -2 ) and 1.4 times of PtCo TONPs (5.6 A·m -2 ), respectively. The mass activity decreases by only 30% after 2,000 cycles, while it is 45% and 99% (nearly inactive) for PtCo TONPs and commercial Pt/C catalysts, respectively.

Reducing the cost and improving the electrocatalytic activity are the key to developing high efficiency electrocatalysts for oxygen evolution reaction (OER). Here, bimetallic NiFe-based metal-organic framework (MOF) was prepared by solvothermal method, and then used as precursor to prepare NiFe-based MOF-derived materials by pyrolysis. The effects of different metal ratios and pyrolysis temperatures on the sample structure and OER electrocatalytic performance were investigated and compared. The experimental results showed that when the metal molar ratio was Fe: Ni = 1:5 and the pyrolysis temperature was 450°C, the sample (FeNi 5 -MOF-450) exhibits a composite structure of NiFe 2 O 4 /FeNi 3 /C and owns the superior electrocatalytic activity in OER. When the current density is 100 mA·cm −2 , the overpotential of the sample was 377 mV with Tafel slope of 56.2 mV·dec −1 , which indicates that FeNi 5 -MOF-450 exhibits superior electrocatalytic performance than the commercial RuO 2 . Moreover, the long-term stability of FeNi 5 -MOF-450 further promotes its development in OER. This work demonstrated that the regulatory methods such as component optimization can effectively improve the OER catalytic performance of NiFe-based MOF-derived materials.