Pt-based Catalysts Research Articles

Enhancing CO tolerance in hydrogen oxidation reaction through synergy of surface-modified MoOx with PtRu alloy

Even trace amounts of CO impurities present in low-cost crude hydrogen can severely poison Pt-based catalysts. For proton exchange membrane fuel cells (PEMFCs), the development of hydrogen oxidation reaction (HOR) catalysts capable of enduring CO contamination is of significant economic importance. In this study, we propose a new strategy to synergistically enhance the CO tolerance of PtRu alloys by incorporating MoOx. The MoOx modified on PtRu/C catalysts can initiate the oxidation of CO adsorbed on its surface at potentials as low as 0.125 V. The synergy effect of MoOx and bifunctional PtRu ensures sufficient HOR stability even under hydrogen containing high CO concentrations. The resulting PtRu-MoOx/C catalyst exhibits a 4.6-fold increase in remained HOR current compared to commercial PtRu/C, after two hours in a hydrogen environment containing 10,000 ppm CO. Under typical testing condition of H2/1,000 ppm CO, PtRu-MoOx/C maintains over 80 % of the initial current density even after ten hours, significantly outperforming PtRu/C (30 %) and most previously reported catalysts.

Cobalt Nitride-Implanted PtCo Intermetallic Nanocatalysts for Ultrahigh Fuel Cell Cathode Performance.

Stable and active oxygen reduction electrocatalysts are essential for practical fuel cells. Herein, we report a novel class of highly ordered platinum-cobalt (Pt-Co) alloys embedded with cobalt nitride. The intermetallic core-shell catalyst demonstrates an initial mass activity of 0.88 A mgPt-1 at 0.9 V with 71% retention after 30,000 potential cycles of an aggressive square-wave accelerated durability test and loses only 9% of its electrochemical surface area, far exceeding the US Department of Energy 2025 targets, with unprecedented stability and only a minimal voltage loss under practical fuel cell operating conditions. We discover that regulating the atomic ordering in the core results in an optimal lattice configuration that accelerates the oxygen reduction kinetics. The presence of cobalt nitride decorated within PtCo superlattices guarantees a larger barrier to Co dissolution, leading to the excellent endurance of the electrocatalysts. This work brings up a transformative structural engineering strategy for rationally designing high-performing Pt-based catalysts with a unique atomic configuration for broad practical uses in energy conversion technology.

Unlocking Superior Hydrogen Oxidation and CO Poisoning Resistance on Pt Enabled by Tungsten Nitride-Mediated Electronic Modulation.

Enhancing the activity and CO poisoning resistance of Pt-based catalysts for the anodic hydrogen oxidation reaction (HOR) poses a significant challenge in the development of proton exchange membrane fuel cells. Herein, we leverage theoretical calculations to demonstrate that tungsten nitride (WN) can intricately modulate the electronic structure of Pt. This modulation optimizes the hydrogen adsorption, significantly boosting HOR activity, and simultaneously weakens the CO adsorption, markedly improving resistance to CO poisoning. Through prescreening with rational design, we synthesized an efficient catalyst comprising a minimal Pt content (only 1.4 wt %) supported on the small-sized WN/reduced graphite oxide (Pt@WN/rGO). As anticipated, this catalyst showcases a remarkable acidic HOR mass activity of 3060 A gPt-1, which is approximately 11.8 times greater than that of the commercial 20 wt % Pt/C catalyst. Impressively, it maintains high activity with 98.2% retention even in the presence of 1000 ppm of CO, indicating exceptional poison resistance. Operando synchrotron radiation analyses reveal that WN harmonizes the electron state of Pt during electrochemical reactions, optimizing hydrogen adsorption/desorption dynamics. This leads to a lower peak potential of CO stripping on Pt@WN/rGO compared to that on Pt/rGO, suggesting that WN mitigates competitive CO adsorption and enhances the availability of hydrogen adsorption sites on Pt. The synergistic effect significantly accelerates HOR activity and increases antipoisoning efficacy. The assembled PEMFC demonstrates substantial tolerance to CO concentration from 10 to 1000 ppm in the H2/CO mixture.

A Review of Stoichiometric Nickel Sulfide-Based Catalysts for Hydrogen Evolution Reaction in Alkaline Media

Efficient and cost-effective catalysts for hydrogen evolution reaction (HER) are essential for large-scale hydrogen production, which is a critical step toward reducing carbon emissions and advancing the global transition to sustainable energy. Nickel sulfide-based catalysts, which exist in various stoichiometries, show promise for HER in alkaline media. However, as single-phase materials, they do not demonstrate superior activity compared to Pt-based catalysts. This review highlights recent strategies to enhance the HER performance of nickel sulfides, including heteroatom doping, heterostructure construction, and vacancy engineering, tailored to their different stoichiometric ratios. The study also examines synthesis methods, characterizations, and their impact on HER performance. Furthermore, it discusses the challenges and limitations of current research and suggests future directions for improvement.

Highly stable and active catalyst in fuel cells through surface atomic ordering.

Shape-controlled alloy nanoparticle catalysts have been shown to exhibit improved performance in the oxygen reduction reaction (ORR) in liquid half-cells. However, translating the success to catalyst layers in fuel cells faces challenges due to the more demanding operation conditions in membrane electrode assembly (MEA). Balancing durability and activity is crucial. Here, we developed a strategy that limits the atomic diffusion within surface layers, fostering the phase transition and shape retention during thermal treatment. This enables selective transformation of platinum-iron nanowire surfaces into intermetallic structures via atomic ordering at a low temperature. The catalysts exhibit enhanced MEA stability with 50% less Fe loss while maintaining high catalytic activity comparable to that in half-cells. Density functional calculations suggest that the ordered intermetallic surface stabilizes morphology against rapid corrosion and improves the ORR activity. The surface engineering through atomic ordering presents potential for practical application in fuel cells with shape-controlled Pt-based alloy catalysts.

Ceria-zirconia solid solution supported platinum catalysts for toluene oxidation: Studying the improved catalytic activity by tungsten addition

The catalytic oxidation of toluene at low temperatures is still an urgent issue to be solved. The key to addressing this issue is the preparation of a high-efficiency catalyst. Herein, ceria-zirconia (CZ) solid solution supported platinum (Pt) catalysts were prepared by citric acid (C)-assisted impregnation method. Surprisingly, the catalytic oxidation activity of the catalyst for toluene combustion significantly improved after introducing W into Pt-C/CZ. In addition, introducing W improved the redox property of the Pt-based catalyst, optimized the distribution of the oxygen vacancies, increased the average particle size of the catalyst particle, modulated the valence state and electronic structure of Pt, elevated the surface lattice oxygen activity, increased the number of surface moderate acidic sites and enhanced toluene adsorption capacity. In this study, the electronic structure of the Pt active site is modulated by introducing a W promoter, providing valuable guidance for the rational design of efficient noble metal catalysts.

Fluorine-Doped Carbon Support Enables Superfast Oxygen Reduction Kinetics by Breaking the Scaling Relationship.

It is well-established that Pt-based catalysts suffer from the unfavorable linear scaling relationship (LSR) between *OOH and *OH (ΔG(*OOH)=ΔG(*OH)+3.2±0.2 eV) for the oxygen reduction reaction (ORR), resulting in a great challenge to significantly reduced ORR overpotentials. Herein, we propose a universal and feasible strategy of fluorine-doped carbon supports, which optimize interfacial microenvironment of Pt-based catalysts and thus significantly enhance their reactive kinetics. The introduction of C-F bonds not only weakens the *OH binding energy, but also stabilizes the *OOH intermediate, resulting in a break of LSR. Furthermore, fluorine-doped carbon constructs a local super-hydrophobic interface that facilitates the diffusion of H2O and the mass transfer of O2. Electrochemical tests show that the F-doped carbon-supported Pt catalysts exhibit over 2-fold higher mass activities than those without F modification. More importantly, those catalysts also demonstrate excellent stability in both rotating disk electrode (RDE) and membrane electrode assembly (MEA) tests. This study not only validates the feasibility of tuning the electrocatalytic microenvironment to improve mass transport and to break the scaling relationship, but also provides a universal catalyst design paradigm for other gas-involving electrocatalytic reactions.

Boosting HER performance by using plasma prepared N-doped CNTs to support Pt nanoparticles

Developing highly-efficient and stable Pt-based catalysts towards alkaline hydrogen evolution reaction (HER) offers a promising strategy for future renewable energy. In this work, radio-frequency (RF) cold plasma-prepared N-doped MWCNTs were adopted to support Pt nanoparticles (NPs) (Pt/NCNTs) via pretreating MWCNTs with RF nitrogen plasma and combining with traditional thermal reduction method. The as-synthesized Pt/NCNT featured an ultra-small size of Pt NPs (1.5 nm) and plentiful doped nitrogen, exhibiting ultra-low overpotential of 28 mV@10 mA cm−2 and ultra-high mass activity of 3.2 A mg Pt−1@100 mA in 1 M KOH solution, which are superior to those of commercial 20 wt% Pt/C catalyst. This is because RF plasma can realize fast, high-efficient and specific N-doping structure of MWCNTs. The lone electron pairs of N species (mainly pyri-N and pyrr-N) on MWCNTs surface transfer to the empty orbitals of Pt NPs, forming a strong coordination effect between Pt and nitrogen, thereby boosting the alkaline HER catalytic performance.

Sub-10 nm PdNi@PtNi Core–Shell Nanoalloys for Efficient Ethanol Electro-Oxidation

By controlling the structure and composition of Pt-based nanoalloys, the ethanol oxidation reaction (EOR) performances of Pt alloy catalysts can be effectively improved. Herein, we successfully synthesis sub-10 nm PdNi@PtNi nanoparticles (PdNi@PtNi NPs) with a core–shell structure by a one-pot method. The sub 10 nm core–shell nanoparticles possess more effective atoms and exhibit a synergistic effect which can lead to a shift in the d-band center and alter binding energies toward adsorbates. Due to the synergistic effect and unique core–shell structure, the PdNi@PtNi NP catalysts exhibit excellent electrocatalytic performance for ethanol oxidation reactions in alkaline, achieving 9.30 times more mass activity and 7.05 times more specific activity that of the state-of-the-art Pt/C catalysts. Moreover, the stability of PdNi@PtNi NPs was also greatly improved over PtNi nanoparticles, PtPd nanoparticles, and commercial Pt/C. This strategy provides a new idea for improving the electrocatalytic performance of Pt-based catalysts for EORs.

Mo-modified Pt/C electrocatalyst prepared by the catalytic decomposition of molybdenum peroxo-complexes for the hydrogen oxidation reaction with enhanced CO tolerance

Commercial 20 % Pt/C catalyst was modified by molybdenum via catalytic decomposition of peroxocomplexes of molybdenum with the subsequent reduction of the Pt2Mo1/C precursor in H2 flow at 600 °C. The detailed HRTEM, EDX, XRD and XPS studies showed that amorphous molybdenum oxide was deposited on Pt particles surface and partially on carbon support. After reduction of the Pt2Mo1/C precursor, the substantial Mo fraction merges the structure of Pt particles thus forming PtMo alloy with reduced lattice parameter, while the rest of molybdenum covers the surface of PtMo particles as MoO3. The presented method of Mo-modification of Pt-based catalysts provides rather simple way to vary Pt:Mo molar ratio. Electrochemical study revealed that the amount of the surface MoO3 plays a key role in the CO tolerance of the PtMo/C catalyst. As prepared Pt2Mo1/C precursor is 15 times superior to the Pt/C catalyst in the CO-tolerance. After reduction, the Pt2Mo1/C electrocatalyst exhibits extremely high CO-tolerance, more than 100 times higher than that of the pristine commercial platinum catalyst.

Smart utilization of bimetallic NiCo alloy supported carbon dots and sulfur quantum dots derived 3D nanocomposite for oxygen evolution reaction

The increasing demand for highly active and stable electrocatalysts for the oxygen evolution reaction (OER) in future energy-conversion systems has driven researchers to explore novel alternatives to Pt-based catalysts. Among these alternatives, zero-dimensional quantum dots have emerged as promising candidates due to their high surface area and intrinsic electrocatalytic activity, which lead to significant breakthroughs in electrocatalytic performance. Herein, we conducted a preliminary investigation into the application of bimetallic NiCo alloy deposited on metal-free quantum dots (carbon dots and sulfur quantum dots) derived nano sponge for the oxygen evolution reaction. The synthesized NiCo-CDs-800 exhibited remarkable electrocatalytic OER activity, achieving a current density of 10 mA cm−2 with only 221 mV overpotential, far surpassing commercial RuO2 electrocatalysts. The excellent electrocatalytic activity can be attributed primarily to high electrochemically active area (168.97 mF cm−2), the presence of large proportion of oxygen vacancies (68.61 %), rich pyridinic nitrogen structure (29.30 %) with strong water adsorption, and synergistic effect of bimetals as supported by density functional theory calculations. Meanwhile, the newly prepared NiCo-SQDs-700 under the similar procedure demonstrate a satisfied OER performance and competing stability when compared to NiCo-CDs. These findings open a new avenue for the application of metal free CDs and SQDs to the growing family of metal@QDs.

Pt Single Atom-Doped Triphasic VP-Ni3P-MoP Heterostructure: Unveiling a Breakthrough Electrocatalyst for Efficient Water Splitting.

Enhancement of an alkaline water splitting reaction in Pt-based single-atom catalysts (SACs) relies on effective metal-support interactions. A Pt single atom (PtSA)-immobilized three-phased PtSA@VP-Ni3P-MoP heterostructure on nickel foam is presented, demonstrating high catalytic performance. The existence of PtSA on triphasic metal phosphides gives an outstanding performance toward overall water splitting. The PtSA@VP-Ni3P-MoP performs a low overpotential of 28 and 261 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at a current density of 10 and 25 mA cm-2, respectively. The PtSA@VP-Ni3P-MoP (+,-) alkaline electrolyzer achieves a minimum cell voltage of 1.48 V at a current density of 10 mA cm-2 for overall water splitting. Additionally, the electrocatalyst exhibits a substantial Faradaic yield of ≈98.12% for H2 and 98.47% for O2 at a current density of 50 mA cm-2. Consequently, this study establishes a connection for understanding the active role of single metal atoms in substrate configuration for catalytic performance. It also facilitates the successful synthesis of SACs, with a substantial loading on transition metal phosphides and maximal atomic utilization, providing more active sites and, thereby enhancing electrocatalytic activity.

N-doped titanium oxide/carbon composite as supports for platinum catalysts in highly efficient methanol oxidation

The commercialization of direct methanol fuel cells (DMFCs) faces significant challenges due to the susceptibility of conventional platinum-based catalysts to poisoning by intermediates such as CO and HCOO− generated during the methanol oxidation reaction (MOR). This study details the synthesis of a highly porous titanium dioxide/carbon composite (TCC) using NH2-MIL-125(Ti) (MIL = Matérial Institut Lavoisier) as a precursor. To enhance the conductivity and catalytic properties of TCC, a nitriding reaction is conducted in an NH3 atmosphere, producing a nitrogen-doped titanium oxide/carbon composite (N-TCC). The resulting N-TCC is employed as a support for a platinum catalyst to improve MOR performance in DMFCs. The Pt/N-TCC catalyst demonstrates high catalytic performance, achieving a mass activity of 537 mA mg−1 for the MOR, marking a 39 % increase over the commercial Pt/C catalyst. Furthermore, the Pt/N-TCC catalyst exhibits a low onset potential for CO oxidation, a higher If/Ib ratio, and greater stability in chronoamperometry test, indicating high resistance to CO poisoning and enhanced chemical stability. Therefore, N-TCC can be used as a promising support for Pt-based catalysts in DMFC applications.

A Janus Platinum/Tin Oxide Heterostructure for Durable Oxygen Reduction Reaction.

Designing efficient and durable electrocatalysts for oxygen reduction reaction (ORR) is essential for proton exchange membrane fuel cells (PEMFCs). Platinum-based catalysts are considered efficient ORR catalysts due to their high activity. However, the degradation of Pt species leads to poor durability of catalysts, limiting their applications in PEMFCs. Herein, a Janus heterostructure is designed for high durability ORR in acidic media. The Janus heterostructure composes of crystalline platinum and cassiterite tin oxide nanoparticles with carbon support (J-Pt@SnO2/C). Based on the synchrotron fine structure analysis and electrochemical investigation, the crystalline reconstruction and charge redistribution at the interface of Janus structure are revealed. The tightly coupled interface could optimize the valance states of Pt and the adsorption/desorption of oxygenated intermediates. As a result, the J-Pt@SnO2/C catalyst possesses distinguishing long-term stability during the accelerated durability test without obvious degradation after 40000 cycles and keeps the majority of activity after 70000 cycles. Meanwhile, the catalyst exhibits outstanding activity with half-wave potential at 0.905V and a mass activity of 0.355AmgPt -1 (2.7 times higher than Pt/C). The approach of the Janus catalyst paves an avenue for designing highly efficient and stable Pt-based ORR catalyst in the future implementation.

Polyoxometalate-derived anti-aggregation MoC nanoparticles for efficient hydrogen evolution in basic and acidic media

As a cost-effective alternative to Pt-based catalysts, molybdenum carbide (MoC) exhibits considerable potential for catalysing hydrogen evolution reaction (HER) in both alkaline water electrolyzers and proton exchange membrane water electrolyzers. However, achieving ampere-level current densities at low overpotentials remains challenging for MoC-based electrocatalysts. In this study, we utilized electrospinning technology followed by a subsequent heat treatment to successfully synthesize monodisperse MoC nanoparticles (approximately 4.3 nm) embedded in carbon nanofibers. The resultant self-supporting one-dimensional molybdenum carbide@nitrogen-doped carbon nanofiber (MoC-A@NCNF), prepared with polyoxometalate anion (POM) and polyvinylpyrrolidone (PVP), exhibits excellent anti-aggregation behavior. Benefiting from its high specific surface area and one-dimensional conductive network structure, the MoC-A@NCNF displays outstanding hydrogen evolution reaction (HER) performance in both 1 M KOH and 0.5 M H2SO4, achieving overpotentials of 491 mV and 568 mV at a current density of 1 A cm−2, respectively. Furthermore, it exhibits exceptional electrochemical stability during prolonged HER testing under both acidic and alkaline conditions.

Electronic interactions between neighboring functionalized guest Sb single atoms and Pt clusters enhance CO tolerance

Platinum-based (Pt) catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide (CO) poisoning. Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity, selectivity, and durability remains a major challenge. Herein, we propose a strategy to enhance the CO tolerance of Pt clusters (Ptn) by introducing neighboring functionalized guest single atoms (such as Fe, Co, Ni, Cu, Sb, and Bi). Among them, antimony (Sb) single atoms (SAs) exhibit significant performance enhancement, achieving 99% CO selectivity and 33.6% CO2 conversion at 450 °C. Experimental results and density functional theory (DFT) calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters, leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized guest single atoms. The redistribution of 5d electrons weaken both the σ donation and π backdonation interactions, resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity. The redistribution of 5d electrons weaken both the σ donation and π backdonation interactions, resulting in a weakened bond strength with CO. In situ environmental transmission electron microscopy (ETEM) further demonstrates the exception thermal stability of catalyst, even under H2 at 700 ℃. Notably, the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts, including Co/CeO2, Ni/CeO2, Pt/Al2O3, and Pt/CeO2-C. This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts, making their broader applications in various industrial catalysts.

Revealing the mechanism of bifunctional PtLa electrocatalyst for highly efficient methanol oxidation, hydrogen evolution, and coupling reaction

The development of clean energy solutions, such as fuel cells and hydrogen energy, is crucial for addressing the global energy shortage. Platinum (Pt)-based catalysts are widely used in fuel cells and hydrogen energy generation (for example, via water electrolysis). However, reducing the amount of Pt used while maintaining the catalytic performance of such catalysts is essential. Herein, PtLa catalysts (PtxLay/C) doped with rare earth element lanthanum (La) with different Pt/La atomic ratios were synthesized using a simple chemical reduction method, resulting in Pt65La35/C, Pt78La22/C, Pt97La3/C, and Pt100/C. These PtxLay/C catalysts exhibited excellent electrocatalytic activity and stability in methanol oxidation reaction (MOR), hydrogen evolution reaction (HER), and their coupling reaction as MOR||HER under alkaline conditions. The mechanism by which La doping enhances the electrocatalytic properties and stability of Pt-based catalysts was investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), aberration-corrected scanning transmission electron microscopy (AC-STEM), in-situ Fourier transform infrared (FTIR) and operando Raman spectroscopy. For HER, La doping facilitated the adsorption and activation of H2O at Pt sites, improving water dissociation and *OH desorption and reducing Pt poisoning by *OH. This enhances both the catalytic performance and stability of PtxLay/C for HER. Pt78La22/C exhibited a considerably lower overpotential of only 111 mV at 100 mA cm−2 compared to commercial 20 wt% Pt/C (Pt/C-Johnson Matthey (JM)), which requires 153 mV. For MOR, La promotes CO bond cleavage and reduces CO adsorption at the Pt sites, thereby enhancing both the performance and stability of the catalysts. The mass activity (MA) of Pt78La22/C for MOR is 4.44 A mg−1Pt, which is 12.33 times higher than that of Pt/C-JM (0.36 A/mgPt), and surpasses those of Pt65La35/C, Pt97La3/C, and Pt100/C (2.93, 0.24, and 2.91 A mg−1Pt, respectively). Additionally, Pt78La22/C exhibited outstanding catalytic performance for MOR||HER, with a current density of 20 mA cm−2 at 1.030 V, demonstrating good stability with negligible voltage changes after a 15 h chronoamperometry (CA) testing. This study provides a new strategy for synthesizing Pt-based catalysts with enhanced efficiency and low-energy input for HER||MOR.

Natural Abundance 195Pt-13C Correlation NMR Spectroscopy on Surfaces Enabled by Fast MAS Dynamic Nuclear Polarization

Surface organometallic chemistry has developed as an effective strategy for the rational design and synthesis of well-defined, single-site Pt-based heterogeneous catalysts. Given its high sensitivity to changes in electronic structure, 195Pt solid-state NMR spectroscopy offers a unique approach to investigate the chemical structure and local environment of Pt surface sites, providing invaluable insights for establishing structure-activity relationships. However, this approach is typically hindered by severe sensitivity issues, due to the low loading of Pt sites and the often-encountered large 195Pt chemical shift anisotropies. To overcome this limitation, 195Pt NMR signature of surface metal centers can be indirectly detected through protons. Indirect detection on 13C spins, has also been demonstrated to be feasible by combining isotopic labeling with dynamic nuclear polarization (DNP). Here, we extend this methodology to a supported Pt complex at natural abundance. The material was prepared by grafting (COD)PtMeOSi(OtBu)3 (COD = 1,5-cyclooctadiene, Me = methyl and tBu = tert-butyl) onto partially dehydroxylated silica. DNP enhanced two-dimensional through-bond 13C{195Pt} heteronuclear correlation experiments were successfully implemented at fast magic angle spinning. They enabled the detection of the 0.37% NMR-responsive surface species, thereby showcasing the remarkable sensitivity of this approach and its broad applicability. Key bonding information was obtained by measuring the correlated 13C and 195Pt isotopic chemical shifts as well as 1J(13C-195Pt) coupling constants, confirming directly the coordination structure of the surface Pt sites.

Screening Transition-Metal-Incorporated β-AgVO3 for Augmented Oxygen Reduction Activity.

Exploring cost-effective alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR) in fuel cells is crucial for their large-scale deployment in green energy applications. Silver vanadate (AgVO3) is a well-studied material for photocatalytic applications. Here, we investigate the electrocatalytic ORR activity of the thermodynamically stable β phase of AgVO3 through computational modeling based on DFT. It is found that β-AgVO3 exhibits weak catalytic activity for the ORR, with vanadium being the preferable active site. Incorporating single atoms of transition metals at surface-level vacancies in β-AgVO3 significantly modifies the ORR activity. We study the scaling of free energy changes for the ORR intermediates *OOH, *OH, and *O for various transition metals incorporated, which leads to an optimal overpotential for the system. The optimal overpotential thus obtained is remarkably lower than that of pristine β-AgVO3. For the transition metal atoms we consider here, Co-incorporated β-AgVO3 exhibits the best ORR catalytic activity due to its optimal binding of ORR species to the vanadium site. It is also observed that some of the transition metals considered like Re, Rh, Os, or Mn show weak activity, either due to strong or weak binding. Analysis of the electronic structure of the adsorbate-catalyst interface shows a strong correlation between optimal activity and evolution of midgap states in β-AgVO3, due to transition metal incorporation. Our study concludes that the ORR activity of a stable mixed transition metal oxide like β-AgVO3 can be enhanced with a minimal loading of transition metals, which could help in developing a novel series of ORR catalysts.

Decoding the Promotional Effect of Iron in Bimetallic Pt-Fe-nanoparticles on the Low Temperature Reverse Water-Gas Shift Reaction.

The reverse water-gas shift (RWGS) reaction is a key technology of the chemical industry, central to the emerging circular carbon economy. Pt-based catalysts have previously been shown to effectively promote RWGS, especially when modified by promoter elements. However, their active states are still poorly understood. Here, we show that the intimate incorporation of an iron promoter into metal-oxide-supported Pt-based nanoparticles can increase their activity and selectivity for the low temperature reverse water-gas shift (LT-RWGS) substantially and drastically outperform unpromoted Pt-based materials. Specifically, the study explores the promotional effect of iron in Pt-Fe bimetallic systems supported on silica (PtxFey@SiO2) prepared by surface organometallic chemistry (SOMC). The most active catalyst (Pt1Fe1@SiO2) shows high selectivity (>99% CO) toward CO at a formation rate of 0.192 molCO h-1 gcat-1, which is significantly higher than that of monometallic Pt@SiO2 (96% sel. and 0.022 molCO h-1 gcat-1). In-situ diffuse reflectance FT-IR spectroscopy (DRIFTS) and X-ray absorption spectroscopy (XAS) indicate a dynamic process at the catalyst surface under the reaction conditions, revealing distinct reaction pathways for the monometallic Pt@SiO2 and bimetallic PtxFey@SiO2 systems.