Operating fuel cells in alkaline environments permits the use of platinum-group-metal-free (PGM-free) catalysts and inexpensive bipolar plates, leading to significant cost reduction. Of the PGM-free ...catalysts explored, however, only a few nickel-based materials are active for catalyzing the hydrogen oxidation reaction (HOR) in alkali; moreover, these catalysts deactivate rapidly at high anode potentials owing to nickel hydroxide formation. Here we describe that a nickel-tungsten-copper (Ni
WCu
) ternary alloy showing HOR activity rivals Pt/C benchmark in alkaline electrolyte. Importantly, we achieved a high anode potential up to 0.3 V versus reversible hydrogen electrode on this catalyst with good operational stability over 20 h. The catalyst also displays excellent CO-tolerant ability that Pt/C catalyst lacks. Experimental and theoretical studies uncover that nickel, tungsten, and copper play in synergy to create a favorable alloying surface for optimized hydrogen and hydroxyl bindings, as well as for the improved oxidation resistance, which result in the HOR enhancement.
A considerable challenge in the conversion of carbon dioxide into useful fuels comes from the activation of CO2 to CO2.− or other intermediates, which often requires precious‐metal catalysts, high ...overpotentials, and/or electrolyte additives (e.g., ionic liquids). We report a microwave heating strategy for synthesizing a transition‐metal chalcogenide nanostructure that efficiently catalyzes CO2 electroreduction to carbon monoxide (CO). We found that the cadmium sulfide (CdS) nanoneedle arrays exhibit an unprecedented current density of 212 mA cm−2 with 95.5±4.0 % CO Faraday efficiency at −1.2 V versus a reversible hydrogen electrode (RHE; without iR correction). Experimental and computational studies show that the high‐curvature CdS nanostructured catalyst has a pronounced proximity effect which gives rise to large electric field enhancement, which can concentrate alkali‐metal cations resulting in the enhanced CO2 electroreduction efficiency.
The needle has landed: CdS nanostructures with sharp tips can generate large electric fields that lead to increased CO2 concentrations for CO2‐to‐CO conversion. The localized electric fields are significantly enhanced when two nanoneedles are in close proximity. These advantages result in CO2 electrocatalytic reduction with a 95.5±4.0 % CO Faraday efficiency.
Platinum on carbon (Pt/C) catalyst is commercially adopted in fuel cells but it undergoes formidable active‐site poisoning by carbon monoxide (CO). In particular, given the sluggish kinetics of ...hydrogen oxidation reaction (HOR) in anion‐exchange membrane fuel cell (AEMFC), the issues of Pt poisoning and slow rate would combine mutually, notably worsening the device performances. Here we overcome these challenges through incorporating cobalt (Co) into molybdenum‐nickel alloy (MoNi4), termed Co‐MoNi4, which not only shows superior HOR activity over the Pt/C catalyst in alkali, but more intriguingly exhibits excellent CO tolerance with only small activity decay after 10 000 cycles in the presence of 500 parts per million (ppm) CO. When feeding with CO (250 ppm)/H2, the AEMFC assembled by this catalyst yields a peak power density of 394 mW cm−2, far exceeding the Pt/C catalyst. Experimental and computational studies reveal that weakened CO chemisorption originates from the electron‐deficient Ni sites after Co incorporation that suppresses d→CO 2π* back‐donation.
Incorporating Co into MoNi4 nanocatalyst can suppress the d→CO 2π* back donation, leading to excellent CO tolerance. When feeding with CO (250 ppm)/H2, the fuel cell assembled by this catalyst yields a peak power density of 394 mW cm−2, exceeding that of 209 mW cm−2 for the Pt/C catalyst.
Electrochemical carbon dioxide reduction reaction (CO2RR) converts CO2 into value-added chemicals and fuels to realize carbon recycling as a means to solve the problems of renewable energy shortage ...and environmental pollution. Recently, regulation of the oxidation state of catalysts has emerged as an effective method for designing better-performing CO2RR catalysts. The oxidation state of the catalyst was observed to influence the activity and selectivity of CO2RR, which is essentially based on promoting reactant activation, regulating the adsorption of intermediates and facilitating the C–C coupling. The CO2RR performance of various catalysts, such as Cu-based catalysts, non-Cu metal catalysts, atomically dispersed metal catalysts and carbon materials, can be efficiently improved through oxidation state regulation. In this review, we first discuss current understandings on how the oxidation state affects the catalytic properties of catalysts. Then, we summarize recent progress in strategies used to regulate the oxidation state of catalysts and their resultant performances toward CO2RR. In particular, we highlight recent advancements in in situ techniques that are used to uncover the dynamic evolution of the oxidation state of catalysts during CO2RR. We end this review by outlining the challenges and offering our personal perspectives on future research directions in this promising field.
Electrosynthesis of hydrogen peroxide (H2O2) in the acidic environment could largely prevent its decomposition to water, but efficient catalysts that constitute entirely earth‐abundant elements are ...lacking. Here we report the experimental demonstration of narrowing the interlayer gap of metallic cobalt diselenide (CoSe2), which creates high‐performance catalyst to selectively drive two‐electron oxygen reduction toward H2O2 in an acidic electrolyte. The enhancement of the interlayer coupling between CoSe2 atomic layers offers a favorable surface electronic structure that weakens the critical *OOH adsorption, promoting the energetics for H2O2 production. Consequently, on the strongly coupled CoSe2 catalyst, we achieved Faradaic efficiency of 96.7 %, current density of 50.04 milliamperes per square centimeter, and product rate of 30.60 mg cm−2 h−1. Moreover, this catalyst shows no sign of degradation when operating at −63 milliamperes per square centimeter over 100 hours.
A strategy that narrows the interlayer distance of cobalt diselenide (CoSe2) is reported, which enables strong coupling between CoSe2 monolayers. The strongly coupled CoSe2 can catalyze electrosynthesis of H2O2 in acidic media efficiently, which yields Faradaic efficiency of 96.7 %, current density of 50.04 mA cm−2, and product rate of 30.60 mg cm−2 h−1, outperforming all catalysts reported previously in acidic environments.
Selective and efficient catalytic conversion of carbon dioxide (CO2) into value-added fuels and feedstocks provides an ideal avenue to high-density renewable energy storage. An impediment to enabling ...deep CO2 reduction to oxygenates and hydrocarbons (e.g., C2+ compounds) is the difficulty of coupling carbon–carbon bonds efficiently. Copper in the +1 oxidation state has been thought to be active for catalyzing C2+ formation, whereas it is prone to being reduced to Cu0 at cathodic potentials. Here we report that catalysts with nanocavities can confine carbon intermediates formed in situ, which in turn covers the local catalyst surface and thereby stabilizes Cu+ species. Experimental measurements on multihollow cuprous oxide catalyst exhibit a C2+ Faradaic efficiency of 75.2 ± 2.7% at a C2+ partial current density of 267 ± 13 mA cm–2 and a large C2+-to-C1 ratio of ∼7.2. Operando Raman spectra, in conjunction with X-ray absorption studies, confirm that Cu+ species in the as-designed catalyst are well retained during CO2 reduction, which leads to the marked C2+ selectivity at a large conversion rate.
Driver driving style plays an important role in vehicle energy management as well as driving safety. Furthermore, it is key for advance driver assistance systems development, toward increasing levels ...of vehicle automation. This fact has motivated numerous research and development efforts on driving style identification and classification. This paper provides a survey on driving style characterization and recognition revising a variety of algorithms, with particular emphasis on machine learning approaches based on current and future trends. Applications of driving style recognition to intelligent vehicle controls are also briefly discussed, including experts' predictions of the future development.
Transition metal dichalcogenide materials have been explored extensively as catalysts to negotiate the hydrogen evolution reaction, but they often run at a large excess thermodynamic cost. Although ...activating strategies, such as defects and composition engineering, have led to remarkable activity gains, there remains the requirement for better performance that aims for real device applications. We report here a phosphorus-doping-induced phase transition from cubic to orthorhombic phases in CoSe
. It has been found that the achieved orthorhombic CoSe
with appropriate phosphorus dopant (8 wt%) needs the lowest overpotential of 104 mV at 10 mA cm
in 1 M KOH, with onset potential as small as -31 mV. This catalyst demonstrates negligible activity decay after 20 h of operation. The striking catalysis performance can be attributed to the favorable electronic structure and local coordination environment created by this doping-induced structural phase transition strategy.
Electrochemical generation of hydrogen peroxide (H2O2) by two‐electron oxygen reduction offers a green method to mitigate the current dependence on the energy‐intensive anthraquinone process, ...promising its on‐site applications. Unfortunately, in alkaline environments, H2O2 is not stable and undergoes rapid decomposition. Making H2O2 in acidic electrolytes can prevent its decomposition, but choices of active, stable, and selective electrocatalysts are significantly limited. Here, the selective and efficient two‐electron reduction of oxygen toward H2O2 in acid by a composite catalyst that is composed of black phosphorus (BP) nailed chemically on the metallic cobalt diselenide (CoSe2) surface is reported. It is found that this catalyst exhibits a 91% Faradic efficiency for H2O2 product at an overpotential of 300 mV. Moreover, it can mediate oxygen to H2O2 with a high production rate of ≈1530 mg L−1 h−1 cm−2 in a flow‐cell reactor. Spectroscopic and computational studies together uncover a BP‐induced surface charge redistribution in CoSe2, which leads to a favorable surface electronic structure that weakens the HOO* adsorption, thus enhancing the kinetics toward H2O2 formation.
Black phosphorus chemically nailed on metallic cobalt diselenide mediates surface charge redistribution, which enables a selective and efficient two‐electron reduction of oxygen toward hydrogen peroxide (H2O2) in acid. The catalyst exhibits a 91% Faradic efficiency for H2O2 at an overpotential of 300 mV, and a high production rate of ≈1530 mg L−1 h−1 cm−2 in a flow‐cell reactor.
Electrochemical reduction of carbon dioxide (CO2) to value-added chemicals and fuels offers a potential platform to store renewable energy in chemical bonds and thus a route to carbon recycling. Due ...to its high efficiency and reasonable economic feasibility, the conversion of CO2 to carbon monoxide (CO) is considered as the most promising candidate reaction in the industrial market. Recently, the understanding of the basic mechanism of CO2 reduction to CO has become clearer, which has also motivated the design principles for better-performing catalysts including morphology, size, grain boundary, and surface engineering. Various catalysts (noble and non-noble metals, transition metal chalcogenides, carbon materials, and molecular catalysts) have been developed to efficiently catalyze the CO2-to-CO conversion. Here we survey recent key progress in CO2-to-CO conversion in the field of electrocatalytic CO2 reduction. We will highlight the principles of designing electrocatalysts for the selective formation of CO, the influence of electrolytes on the selectivity and conversion rate, and the emerging applications of electrolyzers for large-scale CO production. We finally provide an outlook on several development opportunities that could lead to new advancements in this promising research field.
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