Non-noble Catalysts Research Articles

Single-atom Barium Promoter Enormously Enhanced Non-noble Metal Catalyst for Ammonia Decomposition.

As a well-established topic, single-atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single-atom form, the intrinsic roles of single-atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co-Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co-Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat-1·min-1 at very low temperature (500 °C, GHSV = 840,000 mL·g-1·h-1) and Co-Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non-noble catalysts, and reaches or even exceeds numerous reported Ru-based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co-O-Ba-Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N-H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

Highly Active NiRu/C Cathode Catalyst Synthesized by Displacement Reaction for Anion Exchange Membrane Water Electrolysis.

Anion exchange membrane water electrolysis (AEMWE) is highly promising for cost-effective green hydrogen production due to its basic operating conditions facilitating the use of non-noble catalysts. While non-noble Ni/Fe-based catalysts are utilized at the anode, its cathode catalyst still requires precious Pt. Due to the high cost of Pt and the sluggish hydrogen evolution reaction (HER) at the cathode in basic conditions, developing alternative catalysts to replace Pt is highly important. Here, a synthesis procedure for a Ru-based catalyst is reported and its high activity toward the HER in alkaline media is demonstrated in both half-cell and single-cell tests. The catalyst is synthesized in a two-step approach. A highly dispersed Ni catalyst is prepared on carbon support in the first step. In the second step, Ru is deposited on its surface using a galvanic displacement reaction. The uniqueness of this method is that Ru is deposited over the entire electrically conductive surface, resulting in an isotropic and homogeneous Ru distribution within the catalyst powder. It is demonstrated that this material remarkably outperforms state-of-the-art Pt/C catalysts in half-cell and single-cell tests. The single cell only requires 1.73V at 1A cm-2 with an overall PGM content of 0.05mg cm-2.

Selective adsorption and hydrogenolysis of C-OH bond in biomass derived furanic compounds over Ni-TT-Nb2O5

The selective hydrogenolysis of C-OH in renewable furanic compounds to corresponding high-value products has been attractive yet challenging, and the mechanism remains vague. Herein, a non-noble catalyst (Ni-TT-Nb2O5) was prepared to address this challenge. Batch and continuous reaction results show that Ni-TT-Nb2O5 can selectively hydrodeoxygenate 5-hdyroxymethylfurfural to 5-methylfurfural with a very high selectivity of 99 %. Moreover, Ni-TT-Nb2O5 can also selectively hydrodeoxygenate various furanic, benzenoid and aliphatic alcohols, achieving up to > 95 % selectivity. In-situ FTIR and DFT calculations showed that compared with other Ni-supported (supports = Al2O3, CeO2, SiO2, ZrO2) catalysts, HMF was adsorbed on Ni-TT-Nb2O5 surface via parallel mode exclusively, and the C-OH bond was easier to be activated. This work therefore explained the mechanism of selective hydrogenolysis of C-OH in HMF over Ni-TT-Nb2O5, and offered an advanced approach for the upgrading of C-OH-containing furanic compounds as well as benzenoid and aliphatic alcohols.

Continuous lattice oxygen participation of NiFe stack anode for Sustainable water Splitting

Non-noble anode catalysts exhibit insufficient activity and stability for anion exchange membrane water electrolysis (AEMWE). Accordingly, we propose an electrolyte additive strategy involving NiFe-layered double hydroxide. In situ Raman spectroscopy and 18O isotope labeling experiments reveal that Fe ions in the electrolyte change the oxygen evolution reaction mechanism from adsorbate evolution to the lattice oxygen participation mechanism (LOM). These Fe ions continuously refill Fe vacancies owing to facile metal dissolution via the LOM. In a unit cell, we achieve an excellent cell voltage of 1.73 V and energy conversion efficiency (ECE) of 69.4 % at 3.0 A cm−2, meeting the target set by the U.S. Department of Energy (1.80 V and 69.0 % ECE). Our optimized membrane electrode assembly enhances the cell activity (1.567 V at 1.0 A cm−2; ECE = 76.5 %) and stability (0.125 mVcell h−1 at 0.5 A cm−2 for 500 h) with a 100 cm2 AEMWE stack.

Enhanced selective aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran using Mn-enriched MgSnO3 polymetallic catalyst

Catalytic oxidation of 5-Hydroxymethylfurfural (HMF) feedstock to value-added chemical 2,5-diformylfuran (DFF) is of great importance in biomass valorization. However, it is still challenging to develop non-noble metal-based catalysts for high selectivity of DFF due to the coexistence of other undesired derivatives. In this study, MnxMg1-xSnO3 was prepared by Mn incorporating into the crystalline lattice of MgSnO3, triggering synergetic catalysis for selective aerobic oxidation of HMF to DFF. Among polymetallic oxides with varying Mn-Mg molar ratios, Mn0.67Mg0.33SnO3 (Mn/Mg ratio = 2:1) exhibited the best catalytic activity with DFF yield of 80.6 % and selectivity of 87.5 % at 160 °C for 6 h. It is revealed by various characterization analysis that Mn species in Mn0.67Mg0.33SnO3 could not only act as active sites directly but also promote the transformation of oxygen into singlet oxygen for HMF oxidation. Furthermore, the used Mn0.67Mg0.33SnO3 catalyst could be successfully reactivated through a straightforward two-step regeneration method involving impregnation followed by calcination, demonstrating remarkable stability.

Embedding Single Pd Atoms on NiGa Intermetallic Surfaces for Efficient and Selective Alkyne Hydrogenation.

Catalytic removal of alkynes is essential in industry for producing polymer-grade alkenes from steam cracking processes. Non-noble Ni-based catalysts hold promise as effective alternatives to industrial Pd-based catalysts but suffer from low activity. Here we report embedding of single-atom Pd onto the NiGa intermetallic surface with replacing Ga atoms via a well-defined synthesis strategy to design Pd1-NiGa catalyst for alkyne semi-hydrogenation. The fabricated Pd1Ni2Ga1 ensemble sites deliver remarkably higher specific mass activity under superb alkene selectivity of >96 % than the state-of-the-art catalysts under industry-relevant conditions. Integrated experimental and computational studies reveal that the single-atom Pd synergizes with the neighbouring Ni sites to facilitate the σ-adsorption of alkyne and dissociation of hydrogen while suppress the alkene adsorption. Such synergistic effects confer the single-atom Pd on the NiGa intermetallic with a Midas touch for alkyne semi-hydrogenation, providing an effective strategy for stimulating low active Ni-based catalysts for other selective hydrogenations in industry.

Ozone-Assisted Cu-Based Catalysts for the Efficient Electro-Reforming Glycerol to Formic Acid.

Glycerol electrooxidation reaction (GOR) to produce value-added chemicals, such as formic acid, could make more efficient use of abundant glycerol and meet future demand for formic acid as a fuel for direct or indirect formic acid fuel cells. Non-noble metal Cu-based catalysts have great potential in electro-reforming glycerol to formic acid. However, the high activity, selectivity and stability of Cu based catalysts in GOR cannot be achieved simultaneously. Here, we used ozone-assisted electrocatalyst to convert glycerol to formic acid under alkaline conditions, the onset potential was reduced by 60 mV, the Faraday efficiency (FE) reached 95 %. The catalyst has excellent stability within 300 h at the current density of 10 mA cm-2. The electron spin resonance proved that ozone produced superoxide anion during the GOR. In situ Raman spectroscopy, electrochemical studies showed that glycerol can be activated with ozone in GOR, and the C-C bond can be broken to reduce the polymerization of glycerol on the catalyst surface, so as to produce more formic acid at a lower voltage. Moreover, the removal of dissolved O3 from water can be up to 100 % after 30 minutes of GOR reaction at a solubility of 50 mg L-1 as measured by UV-VIS spectrophotometry.

Double-Shell Co3O4 with Rich Surface Octahedron Oxygen Vacancies for High-Selectivity Electrocatalytic Chlorine Evolution.

The development of non-noble-metal-based chlorine evolution reaction (CER) catalysts with excellent activity, kinetics, and selectivity is urgently needed but still remains a major challenge. In this study, a morphology self-evolving and surface octahedron oxygen-vacancy-generating strategy is applied at double-shell nanospheres to obtain the target hierarchical double-shell Co3O4 nanospheres with abundant surface oxygen vacancies (DS-Co3O4-OVs). The DS-Co3O4-OVs display an overpotential of only 52 mV to reach a current density of 10 mA cm-2 in which an excellent chlorine selectivity of 98.9-99.9% is attained, which is better than that of the commercial RuO2/IrO2. Furthermore, density functional theory calculations demonstrate that the involved oxygen vacancies can not only limit the lattice oxygen mechanism of the oxygen evolution reaction process but also significantly improve the kinetics of the Volmer step to enhance the CER performance. Meanwhile, the unique hierarchical double-shell nanospheres can enhance the mass feeding and promote the rate-determining step of the Krishtalik step chlorine gas desorption reaction for enhanced kinetics. The self-evolution of non-noble catalysts with surface octahedron vacancies and the related exploration of the CER mechanism may provide a novel design idea for CER catalysts.

Silica gel supported Cu nanoparticles for selective reductive etherification of furfural into isopropyl furfuryl ether

Furfural (FF) is one of the important platform molecules of biomass, which can be obtained by hydrolysis from lignocellulose and can produce many high value-added chemicals. In this study, a new 4.5 wt% Cu-supported silica gel (SG) catalyst with dual functions of metal and acid site was prepared by acid-base adsorption impregnation method. Isopropyl furfuryl ether (IPFE) with 80.4 % yield was obtained by one-pot reductive etherification of FF in 2-propanol at 150 °C under 2 MPa H2. The characterization of the catalyst proved that the Cu synthesized by this method was well dispersed, and the average size of Cu NPs was 3.34 nm. The reduction of FF to IPFE in a one-pot reaction system is deduced as follows: the existence of a hydrogenation-etherification pathway (main path) and an acetalization-hydrogenolysis pathway. The study in this paper provides a reference for the development of non-noble metal hydroetherification catalysts.

A Smart Design of Non-Noble Catalysts for Sustainable Propane Dehydrogenation.

Propane dehydrogenation (PDH), an important process for propylene synthesis, relies on expensive noble metals or highly toxic oxides as catalysts. In a recent publication, Gong and co-workers report a breakthrough discovery for PDH by introducing a sustainable catalyst composed of titanium oxide overlayers encapsulating nickel nanoparticles, termed Ni@TiOx. This innovative catalyst showcases exceptional performance in PDH, exhibiting high propylene selectivity and stability under industrially relevant conditions. The study elucidates the role of defective TiOx overlayers and the electronic promotional effect of subsurface Ni in enhancing catalytic activity, translating a traditional model catalyst system into a sustainable industrial catalyst for low-carbon energy and the chemical industry.

Biology-Based Synthesis of Nickel Single Atoms on the Surface of Geobacter sulfurreducens as an Efficient Electrocatalyst for Alkaline Water Electrolysis.

Single-atom metal catalysts are promising electrocatalysts for water electrolysis. Nickel-based electrocatalysts have shown attractive application prospects for water electrolysis. However, synthesizing stable Ni single atoms using chemical and physical approaches remains a practical challenge. Here, a facile and precise method for synthesizing stable nickel single atoms on the surface of Geobacter sulfurreducens using a microbial-mediated extracellular electron transfer (EET) process is demonstrated. It is shown that G. sulfurreducens can effectively anchor nickel single atoms on their surface. X-ray absorption near-edge structure and Fourier-transformed extended X-ray absorption fine structure spectroscopy confirm that the nickel single atom is coordinated to nitrogen in the cytochromes. The as-synthesized nickel single atoms on G. sulfurreducens exhibit excellent bifunctional catalytic properties for alkaline water electrolysis with low overpotential (η) to achieve current density (10mAcm-2) for both hydrogen evolution reactions (η = 80mV) and oxygen evolution reaction (η = 330mV) with minimal catalyst loading of 0.0015mgNicm-2. The nickel single-atom catalyst shows long-term stability at a constant electrode potential. This synthesis method based on the EET capability of electroactive bacteria provides a simple and scalable approach for producing low-cost and highly efficient nonnoble transition metal single-atom catalysts for practical applications.

Nanoarchitectonics of vanadium nanoparticles decorated mesoporous carbon nitride in photocatalytic systems: A study on ethylbenzene oxidation reaction

In this work, we have described the synthesis of vanadium (V) nanoparticles (NPs) anchored on mesoporous graphitic carbon nitride (V@mpg-C3N4) and their uses in photocatalytic ethylbenzene oxidation to the respective acetophenones. The mpg-C3N4 serves as the support for the decoration of V NPs, through a simple impregnation method. Various advanced techniques, such as XRD, UV–vis spectrometry, HRTEM, HAADF-STEM, AC-STEM, elemental mapping, and BET surface area analysis, were employed for the characterization of V@mpg-C3N4. The detailed characterization studies reveal that the V@mpg-C3N4 catalyst has a medium band gap (2.78 eV), a high surface area (76.7 m2g−1), and a mesoporous nature. The V@mpg-C3N4 photocatalysts demonstrated excellent performance in the light-assisted oxidation of ethylbenzene, achieving over 99 % conversion and selectivity for acetophenone in an environmentally friendly solvent (water) using a domestic light source (50 W white light). This developed synthesis strategy will be useful for synthesizing various noble and non-noble metal-based catalysts and their applications in organic transformation and environmental remediation.

Impact of metal oxides on the selectivity of NiBi/C catalysts for high-value C-3 products in glycerol electrooxidation reaction

Enhancing the catalytic efficiency and specificity of non-noble Nickel-based catalysts for glycerol electro-oxidation reaction (GEOR) is an ongoing challenge. Recently, metal oxides have attracted attention due to their unique physical properties, such as chemical stability at high anodic potentials, presence of oxygen vacancies, which can significantly influence reaction kinetics and pathways.In this study, we explored the impact of metal oxides CeO2, SnO2, and Sb2O3 • SnO2 (ATO) on the electrochemical performance and product selectivity of NiBi/C and Ni/C catalysts in glycerol electrooxidation (GEOR). The Ni/C-X and NiBi/C-X (X= CeO2, SnO2, and ATO) catalysts were synthesized through a sodium borohydride reduction method at room temperature and comprehensively characterized using various physiochemical and electrochemical techniques.Among the composite support catalysts, Ni and NiBi/C-X, Ni/C-ATO exhibited the highest peak current density, reaching 96 mA cm-2 at 1.50 V vs. RHE. To further assess the catalysts' performance, continuous electrolysis, coupled with HPLC analysis, was conducted to determine product selectivity. Notably, NiBi/C-ATO demonstrated remarkable selectivity, achieving 100 % lactate selectivity under mild conditions. These findings contribute valuable insights into optimizing non-noble Nickel-based catalysts for GEOR, particularly highlighting the promising performance of Ni/C-ATO in terms of selectivity towards valuable products. The DFT calculations provided insight into the synergistic interactions for GEOR over Ni-Ni and Bi-Bi nanoparticles.

One Iron for Two Iron Sites in a Metal-Organic Framework Toward Simultaneous N2-H2 Activation under Mild Conditions.

Iron-based catalysts play an important role in the ammonia industry. As one of the most abundant iron minerals, Fe3O4 containing FeII and FeIII sites is widely distributed in the earth's crust and even on exoplanets, theoretically giving it both economic and catalytic potentials in ammonia synthesis. However, in the absence of specific active co-catalyst and harsh conditions, Fe3O4 is impossible to achieve ammonia synthesis alone. Here, we designed to activate the relatively inert FeII and FeIII sites in Fe3O4 with a third FeIII site inlayed in a coordination framework (MIL-101(Fe)) to achieve the unpresented multi-site collaborative catalysis. In-depth mechanism study confirmed the roles of three different Fe sites in N2 activation, H2 activation, and product transfer, respectively. Efficient N2-H2 activation to NH3 on the Fe3O4-based catalytic system has been achieved at extremely mild conditions. Our research provides a theoretical basis and a new strategy for designing efficient non-noble metal-based ammonia synthesis catalyst with minimized energy consumption.

Catalytic performance of Cs-V-based non-noble soot oxidation catalyst used for DPF and its enhancement by cerium addition

Non-noble metal catalysts have great potential for controlling soot emissions due to their effective oxidation properties and low cost. This study investigated the characteristics of Cs-V-based non-noble metal soot catalyst and Ce doping enhancement effect through comprehensive characterization of physicochemical properties, catalytic activity evaluation, and density functional theory (DFT) theoretical calculations. The results demonstrate that Ce doping improves the degree of surface particle aggregation and the spatial distribution morphology of Cs-V-based catalyst, with a 36.7 % increase in the specific surface area. Additionally, Ce doping enhances the probability of oxygen adsorption and dissociation activation on the Cs-V-based catalyst, accelerating the soot-oxidation process, improving the soot-oxidation activity, with a decrease in the characteristic temperature T10 (temperature at 10 % conversion rate of soot) from 349.7 ℃ to 281.1 ℃, and decreases the activation energy for soot-oxidation to 5.8 kJ/mol. DFT calculations reveal that Ce doping strengthens the pulling effect of interatomic chemical bonds, facilitating the removal of oxygen atoms and dissociated reactive oxygen (Oasd), resulting in an increase in the adsorption energy of C4 molecules and a shorter bond length between C4 molecules and the catalytic surface, facilitating the desorption of post-oxidation soot products.

CoMo/g-C3N4 as a highly effective, reusable, non-noble metal-based catalyst for H2 production via NaBH4 hydrolysis focused on stationary application under mild conditions: A kinetic study

Among hydrogen storage chemicals for proton exchange membrane fuel cells (PEMFCs), sodium borohydride stands out for yielding exceptionally pure hydrogen. This study synthesized cobalt-molybdenum catalysts supported on g-C3N4 using an ultrasonic-assisted impregnation method. Various CoMo/g-C3N4 catalysts with different CoMo mass ratios were created, all showing high hydrogen production and complete NaBH4 conversion under mild conditions. Catalytic activity depends on the cobalt-molybdenum mass ratio, with optimal performance at a 1:1 ratio (w/w), maintaining up to 83% activity over 5 cycles. The effect of operating conditions on hydrogen release was explored, resulting in the rate law: rH2 = 1.708 × 10-3 [NaBH4]1.25 [Catalyst dosage]1.39 [NaOH]0.44 at 298 K, with a low activation energy of 22.9 kJ mol−1. Molybdenum's promoting effect prevented significant deactivation of the cobalt catalyst, ensuring complete NaBH4 conversion to H2 and good stability over multiple cycles.

Hollow Structure Derived Phosphide Nanosheets for Water Oxidation.

Avoiding the stacking of active sites in catalyst structural design is a promising route for realizing active oxygen evolution reaction (OER). Herein, using a CoFe Prussian blue analoge cube with hollow structure (C-CoFe PBA) as a derived support, a highly effective Ni2P-FeP4-Co2P catalyst with a larger specific surface area is reported. Benefiting from the abundant active sites and fast charge transfer capability of the phosphide nanosheets, the Ni2P-FeP4-Co2P catalyst in 1m KOH requires only overpotentials of 248 and 277mV to reach current density of 10 and 50mA cm-2 and outperforms the commercial catalyst RuO2 and most reported non-noble metal OER catalysts. In addition, the two-electrode system consisting of Ni2P-FeP4-Co2P and Pt/C is able to achieve a current density of 10 and 50mA cm-2 at 1.529 and 1.65V. This work provides more ideas and directions for synthesizing transition metal catalysts for efficient OER performance.

Revealing the Effect of Anion Regulation in NiCo2X4 (X = O, S, Se, Te) on Photoassisted Methanol Electrocatalytic Oxidation.

Designing nonprecious metal anode catalysts for photoassisted direct methanol fuel cells (PDMFCs) remains a challenge. As a semiconductor catalyst with a spinel structure, NiCo2O4 has good methanol catalytic oxidation activity and photocatalytic activity, making it a highly promising anode non-noble metal catalyst for PDMFCs. However, compared with the noble metal catalyst, the photoelectrocatalytic activity remained to be improved. In this report, an anion regulation strategy was adopted to improve the photoassisted methanol electrocatalytic activity. Using a CoNi-Aspartic (CoNi-Asp) nanorod as the precursor, the anion-regulated NiCo2X4 (X = O, S, Se, Te) was prepared by oxidation, sulfuration, selenization, and telluridation reactions. The regulation of anions and their effects on the electronic structure, intermediate product, and photoelectric catalytic performance of NiCo2X4 (X= O, S, Se, Te) was systematically discussed. Photoelectrochemical characterization and adsorption energy of •OH revealing the volcano-like correlation between the anion in NiCo2X4 (X = O, S, Se, Te) and their photoelectrocatalytic performance. The narrowest band gap (2.239 eV), the highest •OH adsorption energy (-3.32 eV), and the highest ratio of Co3+/Co2+ (2.19) ensure the best photoelectric catalytic performance of NiCo2S4, under the visible light irradiation, the photoresponse current density was 1.9 A g-1, the current density at 0.6 V was up to 21.9 A g-1. After 9 h of stability testing, the current retention rate was 80%. This report sheds an idea for the rational design of non-noble anode catalysts for PDMFCs.

Unveiling the mechanistic synergy in Mn-doped NiO catalysts with atomic-burry structure: Enhanced CO oxidation via Ni-OH and Mn bifunctionality

The development of non-noble metal catalysts for low-temperature CO oxidation is a pivotal subject in various disciplines. In this study, an optimized Mn-doped NiO catalyst (Mn-NiO-0.5), prepared via aerosol pyrolysis with an equal molar ratio of Ni to Mn, demonstrates remarkable performance. It achieves an 82 % CO conversion at -20 °C and a 100 % conversion between 10 °C and 800 °C. The catalyst’s turnover frequency (TOF) for CO oxidation significantly surpasses that of previously reported noble-metal-based catalysts, underscoring its superior efficiency. Dynamic analyses suggest that the enhanced catalytic activity is a result of the unique atom burr structure, which presents an extensive surface area replete with abundant active sites. This structural feature is instrumental in maximizing the catalyst’s interaction with CO molecules. Experimental findings, corroborated by density functional theory (DFT) calculations, elucidate the mechanism of CO oxidation on the Mn-NiO-0.5 catalyst. The process is facilitated by the synergistic action of bimetallic sites, where the Ni–OH site acts as the primary adsorption point for CO. Subsequently, the CO is oxidized to bicarbonate through the interaction with the oxygen (O or O2) at adjacent Mn sites. This pioneering study introduces a paradigm-shifting insight: the effectiveness of non-noble metal oxide catalysts can now compete with, and in some cases, outperform their noble metal counterparts. This breakthrough is set to transform the industry, presenting a compelling alternative to conventional noble metal catalysts and propelling the evolution of state-of-the-art environmental conservation technologies.

Fe, N Co-doped amine-functionalized MIL 101(Al)-derived mesoporous carbon-based catalysts as high-performance ORR cathode material for Zn-Air battery

The investigation of effective non-noble metal carbon catalysts for oxygen reduction reactions is of great significance importance in Zn-air batteries. Among them, carbon-based materials obtained from metal-organic frameworks (MOFs) demonstrate outstanding catalytic activity in ORR. However, most MOFs-derived catalysts are microporous, which results in poor mass transfer and low utilization of FeNX active sites. In this study, amine-functionalized MIL 101(Al) (NH2-MIL-101) precursors with mesoporous cage structure are synthesized. N-doped carbon carriers with mesoporou structures are prepared at various pyrolysis temperatures. Subsequently, the carbon materials are doped with Fe(phen)32+ complexes and pyrolyzed once more to fabricate highly efficient Fe-Phen-MIL101 catalyst with abundant FeN active sites. The obtained catalyst has a half-wave potential of 0.86 V, which is higher than that of the commercial Pt/C of 0.82 V. Notably, the assembled liquid Zn-air battery (ZAB) exhibits high power density of 120.6 mW cm−2, specific capacity of 725.17 mAh gZn−1, and remarkable cycling stability.