Cu is the only monometallic catalyst that produces a large amount of hydrocarbon fuels during the CO2 electrochemical reduction reaction (CO2RR). However, the CO2RR mechanism and the impact of ...electrolyte are unclear. In this communication, two important issues regarding the CO2RR on Cu surfaces are studied: (1) the direct observation on reaction intermediates and (2) the role of the electrolyte (KHCO3) in the reaction. Surface-enhanced infrared absorption spectroscopy allows direct observation of several reaction intermediates that have never been detected before, except for the commonly detected CO. Another important finding is that CO2 molecules are mediated to the Cu surface via their equilibrium with bicarbonate anions instead of direct adsorption from the solution. These results shed light on the full understanding of the CO2RR on Cu surfaces and developing more advanced catalysts.
Innovation is the source of social progress, and all walks of life need to cultivate innovative talents. Therefore, it is also very important to cultivate innovative ability in physical education ...students in colleges and universities. The purpose of this paper is to study the cultivation of students’ innovative ability of physical education majors in colleges and universities based on the multimedia environment of the Internet of things and to open up a new path for the cultivation of college students’ innovative ability. In this paper, a terminal collaborative indoor positioning algorithm based on RSSI fingerprint optimization was proposed to study the innovation ability of physical education students in colleges and universities. Through experimental analysis, college A was taken as the research object, and 1500 students were investigated. Innovation had a very important position in the hearts of 76.21% of students, and 3.83% of students believed that innovation was not important. In the minds of most people, innovation was still very important, which showed that schools still had a certain effect on the education of students’ innovative consciousness. The experimental results obtained showed that the Internet of things technology played an important role in the research on the innovation ability of students majoring in physical education in colleges and universities.
Oxygen-containing groups on carbon materials can induce high catalytic activity for some reactions. Herein, on the basis of a series of metal-free single-layer graphene nanodisks (GNDs) with ...different surface contents of oxygen-containing groups for highly efficient electrocatalytic reduction reaction of CO2 (CO2RR) to produce formate (HCOO–), we find that the CO2RR catalytic performance is only positively correlated with the surface content of carboxyl groups. While significantly, the density functional theory calculations demonstrate that the observed high CO2RR catalytic activity originates not from the solo carboxyl or other oxygen-containing groups, but from the synergistic effect between carboxyl groups and adjacent other types of groups (namely, hydroxyl, epoxide, and carbonyl) on GNDs. Inspired by such new knowledge, we further find that if the GND catalyst can “alternate work with rest”, its electrocatalytic activity for CO2RR can be regenerated cyclically via a simple electro-oxidation method to regenerate the surface carboxyl groups, achieving a remarkable long-term durability for CO2RR. Such work deepens our understanding of the role of oxygen-containing groups in catalysis and provides a new strategy for the design and synthesis of high-performance metal-free carbon-based catalysts.
While electrochemical water splitting is one of the most promising methods to store light/electrical energy in chemical bonds, a key challenge remains in the realization of an efficient oxygen ...evolution reaction catalyst with large surface area, good electrical conductivity, high catalytic properties, and low fabrication cost. Here, a facile solution reduction method is demonstrated for mesoporous Co3O4 nanowires treated with NaBH4. The high‐surface‐area mesopore feature leads to efficient surface reduction in solution at room temperature, which allows for retention of the nanowire morphology and 1D charge transport behavior, while at the same time substantially increasing the oxygen vacancies on the nanowire surface. Compared to pristine Co3O4 nanowires, the reduced Co3O4 nanowires exhibit a much larger current of 13.1 mA cm‐2 at 1.65 V vs reversible hydrogen electrode (RHE) and a much lower onset potential of 1.52 V vs RHE. Electrochemical supercapacitors based on the reduced Co3O4 nanowires also show a much improved capacitance of 978 F g‐1 and reduced charge transfer resistance. Density‐functional theory calculations reveal that the existence of oxygen vacancies leads to the formation of new gap states in which the electrons previously associated with the Co‐O bonds tend to be delocalized, resulting in the much higher electrical conductivity and electrocatalytic activity.
A facile NaBH4 reduction method is reported to create oxygen vacancies on the surface of mesoporous Co3O4 nanowires and these are used as efficient water oxidation catalysts and high performance supercapacitor electrodes. The reduced Co3O4 nanowires exhibit substantially enhanced electrochemical performance compared to the pristine Co3O4 nanowires. Calculations show that oxygen vacancies create new defect states located in the band gaps of Co3O4, leading to the substantially enhanced electrochemical performance.
Most electrocatalysts for the ethanol oxidation reaction suffer from extremely limited operational durability and poor selectivity toward the CC bond cleavage. In spite of tremendous efforts over ...the past several decades, little progress has been made in this regard. This study reports the remarkable promoting effect of Ni(OH)2 on Pd nanocrystals for electrocatalytic ethanol oxidation reaction in alkaline solution. A hybrid electrocatalyst consisting of intimately mixed nanosized Pd particles, defective Ni(OH)2 nanoflakes, and a graphene support is prepared via a two‐step solution method. The optimal product exhibits a high mass‐specific peak current of >1500 mA mg−1Pd, and excellent operational durability forms both cycling and chronoamperometric measurements in alkaline solution. Most impressively, this hybrid catalyst retains a mass‐specific current of 440 mA mg−1 even after 20 000 s of chronoamperometric testing, and its original activity can be regenerated via simple cyclic voltammetry cycles in clean KOH. This great catalyst durability is understood based on both CO stripping and in situ attenuated total reflection infrared experiments suggesting that the presence of Ni(OH)2 alleviates the poisoning of Pd nanocrystals by carbonaceous intermediates. The incorporation of Ni(OH)2 also markedly shifts the reaction selectivity from the originally predominant C2 pathway toward the more desirable C1 pathway, even at room temperature.
A hybrid electrocatalyst material is reported, which features small Pd nanoparticles abundantly interfaced with Ni(OH)2 and uniformly supported on graphene nanosheets. The synergy between Pd and Ni(OH)2 leads to dramatically improved electrocatalytic performance of the precious metal for the ethanol oxidation reaction and markedly shifts its selectivity toward the C1 pathway in alkaline solution.
Facile interconversion between CO2 and formate/formic acid (FA) is of broad interest in energy storage and conversion and neutral carbon emission. Historically, electrochemical CO2 reduction reaction ...to formate on Pd surfaces was limited to a narrow potential range positive of −0.25 V (vs RHE). Herein, a boron-doped Pd catalyst (Pd–B/C), with a high CO tolerance to facilitate dehydrogenation of FA/formate to CO2, is initially explored for electrochemical CO2 reduction over the potential range of −0.2 V to −1.0 V (vs RHE), with reference to Pd/C. The experimental results demonstrate that the faradaic efficiency for formate (ηHCOO– ) reaches ca. 70% over 2 h of electrolysis in CO2-saturated 0.1 M KHCO3 at −0.5 V (vs RHE) on Pd–B/C, that is ca. 12 times as high as that on homemade or commercial Pd/C, leading to a formate concentration of ca. 234 mM mg–1 Pd, or ca. 18 times as high as that on Pd/C, without optimization of the catalyst layer and the electrolyte. Furthermore, the competitive selectivity ηHCOO–/ηCO on Pd–B/C is always significantly higher than that on Pd/C despite a decreases of ηHCOO– and an increases of the CO faradaic efficiency (ηCO) at potentials negative of −0.5 V. The density functional theory (DFT) calculations on energetic aspects of CO2 reduction reaction on modeled Pd(111) surfaces with and without H-adsorbate reveal that the B-doping in the Pd subsurface favors the formation of the adsorbed HCOO*, an intermediate for the FA pathway, more than that of *COOH, an intermediate for the CO pathway. The present study confers Pd–B/C a unique dual functional catalyst for the HCOOH ↔ CO2 interconversion.
Facile production of hydrogen at room temperature is an important process in many areas including alternative energy. In this Communication, a potent boron-doped Pd nanocatalyst (Pd-B/C) is reported ...for the first time to boost hydrogen generation at room temperature from aqueous formic acid–formate solutions at a record high rate. Real-time ATR-IR spectroscopy is applied to shed light on the enhanced catalytic activity of B-doping and reveals that the superior activity of Pd-B/C correlates well with an apparently impeded COad accumulation on its surfaces. This work demonstrates that developing new anti-CO poisoning catalysts coupled with sensitive interfacial analysis is an effective way toward rational design of cost-effective catalysts for better hydrogen energy exploitation.
The ethanol oxidation reaction (EOR) has drawn increasing interest in electrocatalysis and fuel cells by considering that ethanol as a biomass fuel has advantages of low toxicity, renewability, and a ...high theoretical energy density compared to methanol. Since EOR is a complex multiple-electron process involving various intermediates and products, the mechanistic investigation as well as the rational design of electrocatalysts are challenging yet essential for the desired complete oxidation to CO2. This mini review is aimed at presenting an overview of the advances in the study of reaction mechanisms and electrocatalytic materials for EOR over the past two decades with a focus on Pt- and Pd-based catalysts. We start with discussion on the mechanistic understanding of EOR on Pt and Pd surfaces using selected publications as examples. Consensuses from the mechanistic studies are that sufficient active surface sites to facilitate the cleavage of the C–C bond and the adsorption of water or its residue are critical for obtaining a higher electro-oxidation activity. We then show how this understanding has been applied to achieve improved performance on various Pt- and Pd-based catalysts through optimizing electronic and bifunctional effects, as well as by tuning their surface composition and structure. Finally we point out the remaining key problems in the development of anode electrocatalysts for EOR.
Formic acid as a natural biomass and a CO
2
reduction product has attracted considerable interest in renewable energy exploitation, serving as both a promising candidate for chemical hydrogen storage ...material and a direct fuel for low temperature liquid fed fuel cells. In addition to its chemical dehydrogenation, formic acid oxidation (FAO) is a model reaction in the study of electrocatalysis of C1 molecules and the anode reaction in direct formic acid fuel cells (DFAFCs). Thanks to a deeper mechanistic understanding of FAO on Pt and Pd surfaces brought about by recent advances in the fundamental investigations, the "synthesis-by-design" concept has become a mainstream idea to attain high-performance Pt- and Pd-based nanocatalysts. As a result, a large number of efficient nanocatalysts have been obtained through different synthesis strategies by tailoring geometric and electronic structures of the two primary catalytic metals. In this paper, we provide a brief overview of recent progress in the mechanistic studies of FAO, the synthesis of novel Pd- and Pt-based nanocatalysts as well as their practical applications in DFAFCs with a focus on discussing studies significantly contributing to these areas in the past five years.
A brief overview is presented on recent progress in mechanistic studies of formic acid oxidation, synthesis of novel Pd- and Pt-based nanocatalysts and their practical applications in direct formic acid fuel cells.
Engineering active grain boundaries (GBs) in oxide-derived (OD) electrocatalysts is critical to improve the selectivity in CO2 reduction reaction (CO2RR), which is becoming an increasingly important ...pathway for renewable energy storage and usage. Different from traditional in situ electrochemical reduction under CO2RR conditions, where some metal oxides are converted into active metallic phases but with decreased GB densities, here we introduce the Li electrochemical tuning (LiET) method to controllably reduce the oxide precursors into interconnected ultrasmall metal nanoparticles with enriched GBs. By using ZnO as a case study, we demonstrate that the LiET-Zn with freshly exposed GBs exhibits a CO2-to-CO partial current of ∼23 mA cm–2 at an overpotential of −948 mV, representing a 5-fold improvement from the OD-Zn with GBs eliminated during the in situ electro-reduction process. A maximal CO Faradaic efficiency of ∼91.1% is obtained by LiET-Zn on glassy carbon substrate. The CO2-to-CO mechanism and interfacial chemistry are further probed at the molecular level by advanced in situ spectroelectrochemical technique, where the reaction intermediate of carboxyl species adsorbed on LiET-Zn surface is revealed.
PDF
