Melamine-assisted solvothermal synthesis of PtNi nanodentrites as highly efficient and durable electrocatalyst for hydrogen evolution reaction

Surfactant-free CuxPty nano-alloys with controllable atomic ratios and their enhanced electrocatalytic activity

The electrocatalytic mechanisms of electrocatalysts were constrained by the disparities between the genuine catalytic interface and construction interface. This work demonstrated the relationship between the CuxPty nano-alloy atomic ratios and their catalytic performance. Firstly, we developed a facile synthesis of surfactant-free CuxPty nano-alloys with tunable Cu atomic ratios (ranging from 35 to 72 at%) under ambient conditions. Considering no surfactant-free was applied, surface active sites were uncovered, which was beneficial to ensured consistency between the calculated interface and the actual interface. Based on the experiment and calculation, the relationship between the Pt loading rate and electrocatalytic activity of CuxPty nano-alloy toward hydrogen evolution reaction (HER) was systematically investigated. Under the acidic media, the over-potential by Cu72Pt28 was 7.17 mV, which was 11.5% by the pure Pt nano-particles (NPs). The lower over-potential could be derived from a favorable d-band center of Cu72Pt28, which accelerated the adsorption and desorption of H+. The correlation between the d-band center and the electrocatalytic activity of CuxPty nano-alloy was investigated. Benefiting from the surfactant-free surface, the CuxPty nano-alloy exhibited a favorable electrocatalytic activity toward methanol detection. With the increase in methanol concentration, the anodic peak for methanol oxidation was linearly increased. The linear relationship endowed the CuxPty nano-alloy with a favorable sensor performance. It is suggested that the CuxPty nano-alloy with a higher Pt atomic ratio showed a wider detection range and the CuxPty nano-alloy with a higher Cu atomic ratio showed an enhanced sensitivity. The superior sensor performances could also be utilized for ethanol detection. This work demonstrated the favorable performance of the surfactant-free CuxPty nano-alloy toward hydrogen generation and alcoholic solution (methanol and ethanol) detection. Considering the experiential results were agreed well with calculation, this work pave the way for designing cost-effective electrocatalysis by optimizing its d band center and maximized active sites.

Synthesis, Structural Analysis, and Peroxidase-Mimicking Activity of AuPt Branched Nanoparticles

Bimetallic nanomaterials have generated significant interest across diverse scientific disciplines, due to their unique and tunable properties arising from the synergistic combination of two distinct metallic elements. This study presents a novel approach for synthesizing branched gold-platinum nanoparticles by utilizing poly(allylamine hydrochloride) (PAH)-stabilized branched gold nanoparticles, with a localized surface plasmon resonance (LSPR) response of around 1000 nm, as a template for platinum deposition. This approach allows precise control over nanoparticle size, the LSPR band, and the branching degree at an ambient temperature, without the need for high temperatures or organic solvents. The resulting AuPt branched nanoparticles not only demonstrate optical activity but also enhanced catalytic properties. To evaluate their catalytic potential, we compared the enzymatic capabilities of gold and gold-platinum nanoparticles by examining their peroxidase-like activity in the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Our findings revealed that the incorporation of platinum onto the gold surface substantially enhanced the catalytic efficiency, highlighting the potential of these bimetallic nanoparticles in catalytic applications.

Nanocomposite Electrocatalysts for Hydrogen Evolution Reactions (HERs) for Sustainable and Efficient Hydrogen Energy-Future Prospects

Hydrogen is considered a good clean and renewable energy substitute for fossil fuels. The major obstacle facing hydrogen energy is its efficacy in meeting its commercial-scale demand. One of the most promising pathways for efficient hydrogen production is through water-splitting electrolysis. This requires the development of active, stable, and low-cost catalysts or electrocatalysts to achieve optimized electrocatalytic hydrogen production from water splitting. The objective of this review is to survey the activity, stability, and efficiency of various electrocatalysts involved in water splitting. The status quo of noble-metal- and non-noble-metal-based nano-electrocatalysts has been specifically discussed. Various composites and nanocomposite electrocatalysts that have significantly impacted electrocatalytic HERs have been discussed. New strategies and insights in exploring nanocomposite-based electrocatalysts and utilizing other new age nanomaterial options that will profoundly enhance the electrocatalytic activity and stability of HERs have been highlighted. Recommendations on future directions and deliberations for extrapolating information have been projected.

Simple pyrolysis of graphene-wrapped PtNi nanoparticles supported on hierarchically N-doped porous carbon for sensitive detection of carbendazim

A novel electrochemical sensor was established based on graphene-wrapped PtNi nanoparticles supported on three-dimensional (3D) N-doped porous carbon (G-PtNi/3D-NPC) for the highly sensitive and selective detection of carbendazim (CBZ). In this sensing system, the encapsulation of PtNi nanoparticles (NPs) by graphene can effectively prevent the aggregation tendency and enhance the structural stability. The hierarchically porous nanostructures have a large specific surface area to expose a large number of active sites and the resulting enhanced electrical conductivity ultimate improves the electrocatalytic activity towards CBZ. Under the optimal conditions, the prepared sensor showed excellent electrochemical responses for the determination of CBZ with a linear range of 0.5-30 μM and lower limit of detection (LOD) of 0.04 μM (S/N = 3). It also shows excellent anti-interference ability at a working potential of 0.74 V. The feasibility of the senor is demonstrated for its practical assays in diluted peach and vegetable samples with acceptable recovery (95.8-97.3 %, peach; 97.2-97.6 %, vegetable) and a relative standard deviation (RSD) below 2.3%.

Enhancing Resistance to Chloride Corrosion by Controlling the Morphologies of PtNi Electrocatalysts for Alkaline Seawater Hydrogen Evolution

A solvothermal method to prepare PtNi alloys that have differing morphologies is described. By adjusting the feed ratio of Pt and Ni precursors in this process, PtNi alloys with different compositions (Pt : Ni atomic ratio from 1 : 3 to 3 : 1) and morphologies (evolution from nanobranches to nanoparticles) are generated. The prepared Pt₄₈ Ni₅₂ alloy, which has a composite morphology comprised of nanobranches and nanoparticles, exhibits superior activity and durability towards the hydrogen evolution reaction (HER) in seawater compared to those of commercial Pt/C catalyst and other PtNi alloys that have different compositions and morphologies. The excellent seawater HER performance of Pt₄₈ Ni₅₂ is ascribed to its nanobranch/nanoparticle morphology that optimally facilitates electron accumulation on Pt, which enhances resistance to chloride corrosion in seawater.

One-pot production of a sea urchin-like alloy electrocatalyst for the oxygen electro-reduction reaction

Designing a cost-effective catalyst with high performance towards the oxygen electro-oxidation reaction (ORR) is of great interest for the development of green energy storage and conversion technologies. We report herein a facile self-assembly strategy in a mild reducing environment to realize an urchin-like NiPt bimetallic alloy with the domination of the (111) facets as an efficient ORR electrocatalyst. In the rotating-disk electrode test, the as-obtained NiPt nanourchins (NUCs)/C catalyst demonstrates an increase in both onset potential (0.96 V_RHE) and half-wave potential (0.92 V_RHE) and a direct four-electron ORR pathway with enhanced reaction kinetics. Additionally, the as-made NiPt NUCs/C electrocatalyst also shows impressive ORR catalytic stability compared to a commercial Pt NPs/C catalyst after an accelerated durability test with 15.29% degradation in mass activity, which is 3.04-times lower than 46.48% of the Pt NPs/C catalyst. The great ORR performance of the as-made catalyst is due to its unique urchin-like morphology with the dominant (111) facets and the synergistic and electronic effects of alloying Ni and Pt. This study not only provides a robust ORR electrocatalyst, but also opens a facile but effective route for fabricating 3D Pt-based binary and ternary alloy catalysts.

Galvanostatically Deposited PtNi Thin-Films as Electrocatalysts for the Hydrogen Evolution Reaction

The synthesis of hybrid platinum materials is fundamental to enable alkaline water electrolysis for cost-effective H2 generation. In this work, we have used a galvanostatic method to co-deposit PtNi films onto polycrystalline gold. The surface concentrations of Ni (ΓNi ) and Pt (ΓPt ) were calculated from electrochemical measurements; the ΓPt /ΓNi ratio and electrocatalytic activity of these materials towards hydrogen evolution reaction (HER) in 1 M KOH show a strong dependence on the current density pulse applied during the electrodeposition. Analysis of the Tafel parameters hints that, on these deposits, HER proceeds through a Volmer-Heyrovsky mechanism. The galvanostatically deposited PtNi layers present a high current output per Pt gram, 3199 A gPt -1 , which is significantly larger compared to other PtNi-based materials obtained by more extended and more complex synthesis methods.

PtNi Alloy Coated in Porous Nitrogen-Doped Carbon as Highly Efficient Catalysts for Hydrogen Evolution Reactions

The development of low platinum loading hydrogen evolution reaction (HER) catalysts with high activity and stability is of great significance to the practical application of hydrogen energy. This paper reports a simple method to synthesize a highly efficient HER catalyst through coating a highly dispersed PtNi alloy on porous nitrogen-doped carbon (MNC) derived from the zeolite imidazolate skeleton. The catalyst is characterized and analyzed by physical characterization methods, such as XRD, SEM, TEM, BET, XPS, and LSV, EIS, it, v-t, etc. The optimized sample exhibits an overpotential of only 26 mV at a current density of 10 mA cm⁻², outperforming commercial 20 wt% Pt/C (33 mV). The synthesized catalyst shows a relatively fast HER kinetics as evidenced by the small Tafel slope of 21.5 mV dec⁻¹ due to the small charge transfer resistance, the alloying effect between Pt and Ni, and the interaction between PtNi alloy and carrier.

Trace Amount of NiP2 Cooperative CoMoP Nanosheets Inducing Efficient Hydrogen Evolution

As a very attractive clean energy, hydrogen has a high energy density and great potential to achieve zero pollution emission. Therefore, the preparation of hydrogen evolution electrocatalysts with excellent performance is an urgent task to ameliorate the global energy shortage and environmental pollution. Here, a trace amount of NiP₂ coupled with CoMoP nanosheets (NCMP) was synthesized by the one-step hydrothermal method and low-temperature phosphidation. Studies have found that although the dosage of NiP₂ is very low, its appearance has been efficient to improve the hydrogen evolution reaction (HER) performance of CoMoP, which may be induced by the synergistic effect of the two different components NiP₂ and CoMoP. To find the superior catalyst, the effect of Ni content on the catalyst performance is also studied, and it is found that when the dosage of Ni is 0.02 mM, NCMP-2 (2 means 0.02 mM) displays the most outstanding overpotential (10 mA cm^-2) of 46 mV.

W2N/WC composite nanofibers as an efficient electrocatalyst for photoelectrochemical hydrogen evolution

A tungsten-based electrocatalyst for hydrogen evolution reaction is vital for developing sustainable and clean energy sources. Herein, W2N/WC composite nanofibers were synthesized through electrospinning technology and simultaneous carbonization and N-doping at high temperature. The composite nanofiber has higher catalytic activity than any simple compound. It exhibits remarkable hydrogen evolution performance in acidic media with a low overpotential of -495 mV, at a current density of -50 mA cm-2. The excellent hydrogen evolution performance of the composite nanofiber could be attributed to the abundant active sites, strong light absorption and fast charge transfer. The method used in this work provides a new possibility for the fabrication of high-performance electrocatalysts rationally.

Hydrogen production from water electrolysis: role of catalysts

As a promising substitute for fossil fuels, hydrogen has emerged as a clean and renewable energy. A key challenge is the efficient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efficient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active, stable, and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use, which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity, stability, and efficiency. This will be followed by outlining current knowledge on the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be discussed. New strategies and insights in exploring the synergistic structure, morphology, composition, and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally, future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efficient production of hydrogen from water splitting electrolysis will also be outlined.

Cubic-like PtCuRu Nanocrystals with High Activity and Stability for Methanol Electro-oxidation

Porous cubic-like PtCu and PtCuRu nanocrystals, which had a similar porous three-dimensional structure, were successfully prepared via the one-pot method. During the growth of the nanocrystals, cetyltrimethylammonium chloride and ascorbic acid were employed as the structure director and assistant reducing agent, respectively. The structure and possible formation of the nanocrystals were investigated. It is worth mentioning that the PtCuRu nanocrystals demonstrated a much better methanol electro-oxidation ability and ultrahigh stability, which displayed 3.4- and 3-fold higher specific and mass activity, respectively, than the commercial Pt/C. The advantage of PtCuRu nanocrystals was possibly ascribed to the synergistic effect of Cu and the porous structure and, more importantly, the presence of Ru that could more efficiently eliminate the harmful intermediates.

Self-Supported FeP-CoMoP Hierarchical Nanostructures for Efficient Hydrogen Evolution

Fabricating highly efficient electrocatalysts for electrochemical hydrogen generation is a top priority to relief the global energy crisis and environmental contamination. Herein, a rational synthetic strategy is developed for constructing well-defined FeP-CoMoP hierarchical nanostructures (HNSs). In general terms, the self-supported Co nanorods (NRs) are grown on conductive carbon cloth and directly serve as a self-sacrificing template. After solvothermal treatment, Co NRs are converted into well-ordered Co-Mo nanotubes (NTs). Subsequently, the small-sized Fe oxyhydroxide nanorods arrays are hydrothermally grown on the surface of Co-Mo NTs to form Fe-Co-Mo HNSs, which are then converted into FeP-CoMoP HNSs through a facile phosphorization treatment. FeP-CoMoP HNSs display high activity for hydrogen evolution reaction (HER) with an ultralow cathodic overpotential of 33 mV at 10 mA cm^-2 and a Tafel slope of 51 mV dec^-1 . Moreover, FeP-CoMoP HNSs also possess an excellent electrochemical durability in alkaline media. First-principles density functional theory (DFT) calculations demonstrate that the remarkable HER activitiy of FeP-CoMoP HNSs originates from the synergistic effect between FeP and CoMoP.

Porous β-Mo2C nanoparticle clusters supported on walnut shell powders derived carbon matrix for hydrogen evolution reaction

Herein, we choose the waste walnut shell as the carbon source, and ammonium heptamolybdate as the molybdenum source to prepare the β-Mo₂C catalyst supported on carbon matrix (Mo₂C@C) by the calcination method for hydrogen evolution reaction (HER). The open pores in the porous Mo₂C nanoparticle clusters can facilitate electrolyte permeation and hydrogen molecules release as well as the carbon matrix can enhance the conductivity. As a result, the optimal Mo₂C exhibits an efficient HER performance, with an overpotential of 140 mV at 10 mA cm^-2 and a Tafel slope of 63 mV dec^-1 as well as excellent electrochemical stability. The strategy changing waste walnut shell into the effective catalysts sets an example for the searching and designing rational energy materials.

Thin NiFeCr-LDHs nanosheets promoted by g-C3N4: a highly active electrocatalyst for oxygen evolution reaction

NiFeCr layered double hydroxides (NiFeCr-LDHs) supported on graphitic carbon nitride (g-C₃N₄) hybrids (NiFeCr-LDHs/g-C₃N₄) are synthesized and used as an electrocatalyst for oxygen evolution reaction (OER) in alkaline media. Effect of g-C₃N₄ on the structure and OER performance of NiFeCr-LDHs are investigated in detail. g-C₃N₄ can promote the formation of thin NiFeCr-LDHs nanosheets, thereby enhancing both the number of active sites and OER activity. X-ray photoelectron spectra measurements confirm the electronic interaction between g-C₃N₄ and NiFeCr-LDHs nanosheets. The OER performance of NiFeCr-LDHs/g-C₃N₄ hybrids highly relates to the weight ratio of g-C₃N₄ to NiFeCr-LDHs. When the weight ratio of g-C₃N₄ to NiFeCr-LDHs is 5%, the corresponding electrocatalyst shows the best OER activity. The component optimized NiFeCr-LDHs/g-C₃N₄ hybrids display the overpotential of ∼223 mV at 10 mA cm^-2 and Tafel slope of 89 mV dec^-1 for OER in 1 M KOH solution, which is better than that of pristine NiFeCr-LDHs, bare g-C₃N₄, and commercial RuO₂.

Hydrogen Production from Ammonia Borane over PtNi Alloy Nanoparticles Immobilized on Graphite Carbon Nitride

Graphite carbon nitride (g-C3N4) supported PtNi alloy nanoparticles (NPs) were fabricated via a facile and simple impregnation and chemical reduction method and explored their catalytic performance towards hydrogen evolution from ammonia borane (AB) hydrolysis dehydrogenation. Interestingly, the resultant Pt0.5Ni0.5/g-C3N4 catalyst affords superior performance, including 100% conversion, 100% H2 selectivity, yielding the extraordinary initial total turnover frequency (TOF) of 250.8 molH2 min−1 (molPt)−1 for hydrogen evolution from AB at 10 °C, a relatively low activation energy of 38.09 kJ mol−1, and a remarkable reusability (at least 10 times), which surpass most of the noble metal heterogeneous catalysts. This notably improved activity is attributed to the charge interaction between PtNi NPs and g-C3N4 support. Especially, the nitrogen-containing functional groups on g-C3N4, serving as the anchoring sites for PtNi NPs, may be beneficial for becoming a uniform distribution and decreasing the particle size for the NPs. Our work not only provides a cost-effective route for constructing high-performance catalysts towards the hydrogen evolution of AB but also prompts the utilization of g-C3N4 in energy fields.

One-pot aqueous synthesis of two-dimensional porous bimetallic PtPd alloyed nanosheets as highly active and durable electrocatalyst for boosting oxygen reduction and hydrogen evolution

Recently, two-dimensional materials have gained increasing research attention due to their large surface area, high physical and chemical stability, and excellent electrocatalytic performances. Herein, we reported a simple and fast one-pot aqueous method for synthesis of two-dimensional porous bimetallic PtPd alloyed nanosheets (NSs) using benzyldimethylhexadecylammonium chloride (HDBAC) as the capping agent and stabilizer. The formation mechanism involved the oriented attachment and self-assembly. The PtPd NSs exhibited excellent oxygen reduction reaction (ORR) activity with the positive shift (c.a. 43 mV) of the half-wave potential in 0.1 M KOH solution, clearly outperforming that of commercial Pt/C (50 wt%). Moreover, the as-prepared catalyst displayed 2.4 times enlargement in mass activity (MA, 382.10 mA mg^-1) and 3.5 times enhancement in specific activity (SA, 0.95 mA cm^-2) relative to those of Pt/C at 0.80 V. Meanwhile, the as-obtained catalyst demonstrated highly boosted hydrogen evolution reaction (HER) in 0.5 M H₂SO₄ electrolyte, surpassing that of Pt/C. These results reveal the practical applications of the catalyst in energy storage and conversion.