Non-noble Metal-based Catalysts Research Articles

Tuning the properties of Ni-based catalyst via La incorporation for efficient hydrogenation of petroleum resin

The hydrogenation of petroleum resin (PR) is an effective process to prepare high value-added hydrogenated PR (HPR). However, the preparation of non-noble metal-based catalysts with high catalytic activity for PR hydrogenation still remains a challenge. Herein, a La promoted Ni-based catalyst is reported through the thermal reduction of quaternary NiLaMgAl-layered double hydroxides (NiLaMgAl-LDHs). The incorporation of La is beneficial to the reduction and stability of Ni particles with reduced particle size, and the increased alkalinity effectively mitigates the breakage of molecular chains of PR. As a result, the La promoted Ni-based catalyst exhibits high catalytic activity and excellent stability for PR hydrogenation. A hydrogenation degree of 95.4% and 96.1% can be achieved for HC 5 PR and HC 9 PR with less reduced softening point, respectively. Notably, the hydrogenation degree still maintains at 92.7% even after 100 hours’ reaction, much better than that without La incorporation or prepared using conventional impregnation method.

Cobalt phosphide with porous multishelled hollow structure design realizing promoted ammonia borane dehydrogenation: Elucidating roles of architectural and electronic effect

Exploring advanced non-noble metal-based catalysts for H2 release from chemical hydrogen storage materials is of paramount importance to boost hydrogen economy. Rationally tailoring over architecture and electronic state promises high-efficiency catalysis. Herein we present, for the first time, delicate engineer of cobalt phosphide with a unique porous, multishelled, and hollow architecture (multishelled Co-P) for dramatically promoting ammonia borane (AB) dehydrogenation. Featuring hollow porous structure and complex nanoconfined interior space, multishelled Co-P possesses abundant accessible active sites and facile mass transfer. Importantly, theoretical calculations decipher that P incorporation in Co-P can modulate electronic structure of Co sites to give promoted H2O adsorption and favorable H2O dissociation kinetics (rate-determining step), thereby facilitating AB dehydrogenation. This study provides a fundamental understanding of correlation between electronic state of Co-P and AB dehydrogenation behavior, and highlights that decent architectural engineering coupled with electronic modulation is an effective protocol to construct advanced catalytic systems.

Electrochemical synergy between FeNi nanoalloy@tungsten carbide on N-doped graphitized carbon layers as an excellent electrocatalyst for oxygen evolution reaction

Reasonable construction of non-noble metal-based catalysts as a substitute to precious metal-based catalysts for the oxygen evolution reaction (OER) in water splitting has been a challenge. Herein, ultrasmall core-shell-structured FeNi encapsulated within tungsten carbide (WC) stabilized in a thin N-doped graphitized carbon layer (NCL) was proposed through a unique one-step encapsulation strategy combined with a high temperature carbonization procedure and tested as an OER catalyst. Physicochemical characterizations of the newly prepared material demonstrate that metal nanoparticles are embedded in the carbon layers of FeNi@WC-NCL, which possess a highly porous structure and large specific surface area. By modulating the electronic effects of both the FeNi alloy and WC, the optimal NiFe@WC-NCL catalyst presents excellent performance with an onset potential of 1.38 V (vs. RHE) and an overpotential of only 279 mV (vs. RHE) at the current density of 10 mA cm−2 towards OER. Moreover, NiFe@WC-NCL exhibits excellent durability after 2000 cycles with a slight overpotential decrease of only 11 mV. Both the property and stability of the proposed catalyst surpass the benchmark RuO2 catalyst, providing great potential as an alternative to precious metal catalysts for the OER.

Two-dimensional porous Cu-CuO nanosheets: Integration of heterojunction and morphology engineering to achieve high-effective and stable reduction of the aromatic nitro-compounds

The morphology and heterojunction engineering are effective ways to boost the performance of Cu-based catalysts. Herein, we have reported the designed synthesis of two-dimensional Cu-CuO heterojunction nanosheets (2D Cu-CuO NS) based on 3-Aminopropyl-triethoxysilane (APTES, KH550) aided synthetic strategy. The APTES can act as both the ligand and alkali (-OH) source to guide the large-scale synthesis of 2D Cu-based precursor, which can transform into 2D Cu-CuO NS by the controllable post-treatment. The Si species from APTES can protect the particles from the severe aggregation and growth, guaranteeing the formation of 2D sheets composed of small-sized Cu-CuO heterojunction (about 20 nm). The heterojunction interfaces can provide plentiful active sites to boost the catalytic ability. The 2D sheets can provide large accessible surface, being conducive to the contact of the catalyst and reactants. Benefiting from above virtues, the 2D Cu-CuO NS showed the superior catalytic performance for the reduction of a series of nitro compounds, being superior to most reported non-noble metal-based catalysts. Notably, it exhibited good re-cycled performance with no obvious performance degradation after 10 consecutive catalysis. The present study will be promising to promote the application of the Cu-based catalysts, due to its ability to control the morphology and potential for the large-scale synthesis. Two-dimensional porous Cu-CuO heterojunction nanosheets (2D Cu-CuO NS) were designed and synthesized with high yield based on 3-aminopropyl-triethoxysilane (KH550) aided synthetic strategy. Due to the 2D porous structure and the synergistic effect of Cu and CuO, the 2D Cu-CuO heterojuntion showed excellent catalytic activity and stability for the reduction of the various aromatic nitro-compounds, being at the forefront of reported non-noble metal catalysts.

Interfacial Atom‐Substitution Engineered Transition‐Metal Hydroxide Nanofibers with High‐Valence Fe for Efficient Electrochemical Water Oxidation

Developing low‐cost electrocatalysts for efficient and robust oxygen evolution reaction (OER) is the key for scalable water electrolysis, for instance, NiFe‐based materials. Decorating NiFe catalysts with other transition metals offers a new path to boost their catalytic activities but often suffers from the low controllability of the electronic structures of the NiFe catalytic centers. Here, we report an interfacial atom‐substitution strategy to synthesize an electrocatalytic oxygen‐evolving NiFeV nanofiber to boost the activity of NiFe centers. The electronic structure analyses suggest that the NiFeV nanofiber exhibits abundant high‐valence Fe via a charge transfer from Fe to V. The NiFeV nanofiber supported on a carbon cloth shows a low overpotential of 181 mV at 10 mA cm−2, along with long‐term stability (>20 h) at 100 mA cm−2. The reported substitutional growth strategy offers an effective and new pathway for the design of efficient and durable non‐noble metal‐based OER catalysts.

Crystalline-amorphous interface of mesoporous Ni2P @ FePOxHy for oxygen evolution at high current density in alkaline-anion-exchange-membrane water-electrolyzer

For industrial high-purity hydrogen production, it is essential to develop low-cost, earth-abundant, highly-efficient, and stable electrocatalysts which deliver high current density (j) at low overpotential (η) for oxygen evolution reaction (OER). Herein, we report an active mesoporous Ni2P @ FePOxHy pre-electrocatalyst, which delivers high j = 1 A cm−2 at η = 360 mV in 1 M KOH with long-term durability (12 days), fulfilling all the desirable commercial criteria for OER. The electrocatalyst shows abundant interfaces between crystalline metal phosphide and amorphous phosphorus-doped metal-oxide, improving charge transfer capability and providing access to rich electroactive sites. Combined with an excellent non-noble metal-based HER catalyst, we achieve commercially required j = 500/1000 mA cm−2 at 1.65/1.715 V for full water-splitting with excellent stability in highly corrosive alkaline environment (30% KOH). The alkaline-anion-exchange-membrane water-electrolyzer (AAEMWE) fabricated for commercial viability exhibits high j of 1 A cm−2 at 1.84 V with long-term durability as an economical hydrogen production method, outperforming the state-of-the-art Pt/C–IrO2 catalyst.

Active sites-rich layered double hydroxide for nitrate-to-ammonia production with high selectivity and stability

Electrochemical nitrate reduction to ammonia (NRA) has attracted increasing attention recently, as it can not only eliminate the harmful nitrate in water, but also produce high value-added ammonia in ambient conditions. Noble metals such as Ru, Pd, Pt, etc., show good activity for NRA but the high price and scarcity restrict their practical applications. Therefore, to develop efficient non-noble metal-based catalysts towards NRA is of great significance. In this contribution, CoFe layered double hydroxide (CoFe LDH) is demonstrated as an efficient non-noble electrocatalyst for NRA. Specifically, NH3 selectivity and Faradaic efficiency of CoFe LDH in alkaline conditions are up to 98.93% and 97.68%, respectively. CoFe LDH also maintains good operation durability during 12 consecutive recycling tests (36 h). It is found that there is strong electronic interaction between Co and Fe species, which accelerates reaction kinetics of CoFe LHD. Density functional theory calculations also suggest that CoFe LDH can favorably promote the adsorption of intermediates (NO3– and NO2–) and desorption of NH3, eventually achieving efficient and selective NH3 production.

Mechanistic understanding and design of non-noble metal-based single-atom catalysts supported on two-dimensional materials for CO2 electroreduction

This review delivers an overview of non-noble metal-based single-atom catalysts (SACs) for CO2RR and provides insights into mechanistic understanding from different aspects.

Role of sulfur vacancies in MoS2 monolayers in stabilizing Co atoms for efficient CO oxidation.

By performing first-principles calculations, a MoS2 monolayer with a Co atom doped at the sulfur defect (Co-SMoS2) was investigated as a single-atom catalyst (SAC) for CO oxidation. The Co atom is strongly constrained at the S-vacancy site of MoS2 without forming clusters by showing a high diffusion energy barrier, ensuring good stability to catalyze CO oxidation. The CO and O2 adsorption behavior on Co-SMoS2 surface and four reaction pathways, namely, the Eley-Rideal (ER), Langmuir-Hinshelwood (LH), trimolecular Eley-Rideal (TER) as well as the New Eley-Rideal (NER) mechanisms are studied to understand the catalytic activity of Co-SMoS2 for CO oxidation. The CO oxidation is more likely to proceed through the LH mechanism, and the energy barrier for the rate-limiting step is only 0.19 eV, smaller than that of noble metal-based SACs. Additionally, the NER mechanism is also favorable with a low energy barrier of 0.26 eV, indicating that the Co-SMoS2 catalyst can effectively promote CO oxidation at low temperatures. Our investigation demonstrates that the S-vacancy of MoS2 plays an important role in enhancing the stability and catalytic activity of Co atoms and Co-SMoS2 is predicted to be a promising catalyst for CO oxidation.

Multiple regulation towards an all-in-one NiCuMo/MoOx heterostructure for improving alkaline hydrogen oxidation.

Herein, we report a multiple regulation strategy towards an all-in-one NiCuMo/MoOx heterostructure for the HOR, which exhibits ultrahigh HOR activity (j@0.05V = 4.63 mA cm-2) and excellent durability for almost 24 h for the synergistic regulation of Mo and Cu on the Ni electrode. This study provides a new strategy for designing efficient non-noble metal-based HOR catalysts.

Recent advances in non-noble metal-based oxide materials as heterogeneous catalysts for C-H activation.

As the world moves towards a more sustainable future, it is desirable to replace the homogeneous catalytic processes and conventional industrial processes with energy-efficient, cost-effective, and greener heterogeneous processes. In heterogeneous catalysis, non-noble metal-based oxide catalysts have been gaining traction recently, as they are affordable, highly stable, and thus appealing for different industrial uses. C-H activation is crucial to numerous organic reactions such as hydrogenation, oxidation, reduction, oxidative coupling, substitution, and C-C coupling. However, it is a challenging task due to its high bond energy and high kinetic barrier of C-H bond cleavage, making it inert in most conventional processes, thereby requiring efficient catalysts. In recent years, non-noble metal-based oxides have made a huge difference in the reactivity of the C-H bond through their tailored surface area, surface charge, redox properties, and oxygen vacancies. In this perspective article, we discuss the application of nanostructured non-noble metal oxides with tailored surface properties through nano-structuring, doping, vacancy creation, and heterostructure formation in reactions involving C-H activation as the key step. Specifically, we focus on the essential surface properties of catalysts that play a major role in the C-H activation reaction for sustainable industrial applications.

CrOx decoration on Fe/TiO2 with tunable and stable oxygen vacancies for selective oxidation of glycerol to lactic acid

Non-noble metal-based catalysts catalyze the conversion of glycerol to lactic acid.

Highly effective and chemoselective hydrodeoxygenation of aromatic alcohols.

Effective hydrodeoxygenation (HDO) of aromatic alcohols is very attractive in both conventional organic synthesis and upgrading of biomass-derived molecules, but the selectivity of this reaction is usually low because of the competitive hydrogenation of the unsaturated aromatic ring and the hydroxyl group. The high activity of noble metal-based catalysts often leads to undesired side reactions (e.g., saturation of the aromatic ring) and excessive hydrogen consumption. Non-noble metal-based catalysts suffer from unsatisfied activity and selectivity and often require harsh reaction conditions. Herein, for the first time, we report chemoselective HDO of various aromatic alcohols with excellent selectivity, using porous carbon–nitrogen hybrid material-supported Co catalysts. The C–OH bonds were selectively cleaved while leaving the aromatic moiety intact, and in most cases the yields of targeted compounds reached above 99% and the catalyst could be readily recycled. Nitrogen doping on the carbon skeleton of the catalyst support (C–N matrix) significantly improved the yield of the targeted product. The presence of large pores and a high surface area also improved the catalyst efficiency. This work opens the way for efficient and selective HDO reactions of aromatic alcohols using non-noble metal catalysts.

Fe/Co/N-C/graphene derived from Fe/ZIF-67/graphene oxide three dimensional frameworks as a remarkably efficient and stable catalyst for the oxygen reduction reaction.

The development of non-noble metal catalysts with high-performance, long stability and low-cost is of great importance for fuel cells, to promote the oxygen reduction reaction (ORR). Herein, Fe/Co/N–C/graphene composites were easily prepared by using Fe/ZIF-67 loaded on graphene oxide (GO). The Fe/Co/porous carbon nanoparticles were uniformly dispersed on graphene with high specific surface area and large porosity, which endow high nitrogen doping and many more active sites with better ORR performance than the commercial 20 wt% Pt/C. Therefore, Fe/Co/N–C/graphene composites exhibited excellent ORR activity in alkaline media, with higher initial potential (0.91 V) and four electron process. They also showed remarkable long-term catalytic stability with 96.5% current retention after 12 000 s, and outstanding methanol resistance, compared with that of 20 wt% Pt/C catalysts. This work provides an effective strategy for the preparation of non-noble metal-based catalysts, which could have significant potential applications, such as in lithium–air batteries and water-splitting devices.

In-situ construction of 3D hetero-structured sulfur-doped nanoflower-like FeNi LDH decorated with NiCo Prussian blue analogue cubes as efficient electrocatalysts for boosting oxygen evolution reaction

At present, it is urgent for us to develop non-noble metal-based catalysts with abundant reserves and high efficiency towards oxygen evolution reaction (OER) in water electrolysis devices. Herein, cubic NiCo-Prussian blue analogue (PBA)/ flower-like FeNi layered double hydroxide (LDH) heterostructure was facilely in-situ formed on porous nickel foam (NF) via hydrothermal strategy coupled by subsequent sulfurizing treatment (named as S-FeNi LDH@PBA/NF), showing largely facilitated electron transfer over homogeneous counterpart. Also, we investigated the effects of different Fe/Ni feeding ratios on their catalytic properties in some detail. The as-prepared S-FeNi LDH@PBA/NF demonstrated the superior OER activity (e.g. only 243 mV of overpotential required for 50 mA cm−2) and stability. Accordingly, using the catalyst as anode, the home-assembled S-FeNi LDH@PBA/NF//Pt/C/NF electrolyzer exhibited small Tafel slope (83.1 mV dec–1) and ultra-stability, showing the potential feasibility in practical water electrolysis. This strategy provides a hopeful model to enhance the OER performance by effectively constructing advanced catalyst with promising heterostructure and optimal electronic structure.

Non-noble Nickel-Modified Covalent Organic Framework for Partial Hydrogenation of Aromatic Terminal Alkynes.

Developing non-noble metal-based catalysts with excellent performance for selective hydrogenation of alkynes under mild reaction conditions is highly desirable but still faces challenges. Herein, a non-noble nickel-modified covalent organic framework (Ni/COF) had been synthesized through a facile post-modified method and followed by reduction at a different temperature under a H2/Ar atmosphere. The as-prepared catalysts were characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller, and Fourier transforms infrared, and the optimal H350-Ni/COF presents excellent catalytic performance in the semihydrogenation of a series of aromatic terminal alkyne substrates, particularly in the partial hydrogenation of phenylacetylene with nearly full conversion and 85% selectivity toward styrene under mild reaction conditions (10 bar of H2, 100 °C, and 1 h). Moreover, such a catalyst also exhibited satisfying stability after three consecutive cycles.

Integration of heterointerface and porosity engineering to achieve efficient hydrogen evolution of 2D porous NiMoN nanobelts coupled with Ni particles

The design of the electrocatalysts with the plentiful heterojuctional interface and large-accessible surface is desired to boost the HER performance, but it remains a challenge. Herein, we showed the design of 2D Ni/Ni0.2Mo0.8N porous heterojunction nanobelts as effective catalyst for the HER. The intimate combination of Ni and Ni0.2Mo0.8N can make the formation of the heterojuctional interface with plentiful active sites. The 2D porous structure can provide large accessible surface with less resistance for the transmission of the electrolytes, thus promoting the mass/charge transfer. The ratio of Ni and Ni0.2Mo0.8N can be easily tuned by regulating the precursor composition, which is important to give catalysts with optimized interface and suitable pores. Density functional theory calculations reveal that the interaction between Ni and Ni0.2Mo0.8N at the heterointerface can largely improve the intermediate H* adsorption kinetics (ΔGH* = -0.07 eV). Due to the above advantages, the optimized catalysts exhibited excellent HER activity with a low overpotential of 48 mV in 1 M KOH at 10 mA cm−2 (without iR correction), which is superior to the most reported non-noble metal-based catalysts, and the long-term durability with no obvious degradation after continual operation of 48 h Notably, an electrolyzer assembled by the optimized Ni/Ni0.2Mo0.8N cathode with NiFe-LDH anode only requires a low operating voltage of 1.47 V to deliver 10 mA cm−2 in 1 M KOH, surpassing the corresponding Pt/NF||RuO2/NF electrolyzer (1.61 V) and most of reported electrolyzers.

Design heterostructure of NiS–NiS2 on NiFe layered double hydroxide with Mo doping for efficient overall water splitting

NiFe layered double hydroxide (LDH)-based materials arouse great attention because of their outstanding catalytic activity for oxygen evolution reaction (OER) under alkaline conditions. However, its catalytic activity for hydrogen evolution reaction (HER) under alkaline conditions is relatively poor. Herein, to improve the HER catalytic activity of NiFe LDH under alkaline conditions, we design a heterostructure of NiS and NiS2 on NiFe LDH and successfully achieve Mo element doping. The catalyst named NiFe-LDH@Mo–NiS–NiS2/NF possesses a three-dimensional nano-flower-like structure and shows an outstanding catalytic performance for both HER and OER. Specifically, in 1 M KOH solution, it requires the low overpotentials of 261 and 120 mV to achieve the current density of 50 and 10 mA cm−2 for OER and HER, respectively. Simultaneously, when NiFe-LDH@Mo–NiS2–NiS/NF is used as the bifunctional catalysts, it only needs a low voltage of 1.63 V to achieve a current density of 10 mA cm−2. The outstanding catalytic performance is attributed to its special heterostructure and the synergy between Mo and NiSx, resulting in comparability with most reported non-noble metal-based catalysts. The doping of metal elements and the construction of heterostructures provide new ideas for the structure regulation and performance improvement of bifunctional electrocatalysts.

A telluride-doped porous carbon as highly efficient bifunctional catalyst for rechargeable Zn-air batteries

The development of high-efficiency, low-cost, and stable bifunctional catalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance to the large-scale application of zinc–air batteries. Here we synthesized a telluride (Te)-doped porous carbon catalyst (ZnCo-Te@NC) through pyrolyzing ZnCo-MOF-coated Te nanotubes. The as-prepared ZnCo-Te@NC exhibited excellent bifunctional electrocatalytic performance with an impressive half-wave potential (E1/2) of 0.873 V for ORR and a low overpotential of 400 mV at 10 mA cm−2 for OER, outperforming most non-noble metal-based catalysts previously reported. When using ZnCo-Te@NC as the air cathode catalyst in a self-assembled battery, it demonstrated smaller charge-discharge voltage gap (0.932 V at 50 mA cm−2) and higher peak power density (259.7 mW cm−2) with robust long-term (100 h) cycle stability, surpassing the benchmark precious metal catalyst-based batteries. This is the first report that telluride has been doped into a highly graphitized porous carbon for use in zinc-air batteries. This work provides an effective strategy to develop high graphitized carbon materials by telluride modification to enhance the performance of bifunctional electrocatalysts for Zn–air batteries.

Hierarchical N-Doped CuO/Cu Composites Derived from Dual-Ligand Metal-Organic Frameworks as Cost-Effective Catalysts for Low-Temperature CO Oxidation.

Development of multi-ligand metal–organic frameworks (MOFs) and derived heteroatom-doped composites as efficient non-noble metal-based catalysts is highly desirable. However, rational design of these materials with controllable composition and structure remains a challenge. In this study, novel hierarchical N-doped CuO/Cu composites were synthesized by assembling dual-ligand MOFs via a solvent-induced coordination modulation/low-temperature pyrolysis method. Different from a homogeneous system, our heterogeneous nucleation strategy provided more flexible and cost-effective MOF production and offered efficient direction/shape-controlled synthesis, resulting in a faster reaction and more complete conversion. After pyrolysis, they further transformed to a unique metal/carbon matrix with regular morphology and, as a hot template, guided the orderly generation of metal oxides, eliminating sintering and agglomeration of metal oxides and initiating a synergistic effect between the N-doped metal oxide/metal and carbon matrix. The prepared N-doped CuO/Cu catalysts held unique water resistance and superior catalytic activity (100% CO conversion at 140 °C).