Atomic Layer Deposition of TiO2 on Si Window Enables In Situ ATR-SEIRAS Measurements in Strong Alkaline Electrolytes.

The Si window is the most widely used internal reflection element (IRE) for electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), yet local chemical etching on Si by concentrated OH- anions bottlenecks the reliable application of this method in strong alkaline electrolytes. In this report, atomic layer deposition of a 25 nm nonconductive TiO2 barrier layer on the reflecting plane of a Si prism is demonstrated to address this challenge. In situ ATR-SEIRAS measurement on a Au film electrode with the Si/TiO2 composite IRE in 1 M NaOH reveals reversible global spectral features without spectral distortion at 1000-1300 cm-1, in stark contrast to those obtained with a bare Si window. By applying this structured ATR-SEIRAS, ethanol electrooxidation on a Pt/C catalyst in 1 and 5 M NaOH is explored, manifesting that such high pH values prevent the adsorption of as-formed acetate in the C2 pathway but not that of CO intermediate in the C1 pathway.

Uncovering Photoelectronic and Photothermal Effects in Plasmon-Mediated Electrocatalytic CO2 Reduction.

Plasmon-mediated electrocatalysis that rests on the ability of coupling localized surface plasmon resonance (LSPR) and electrochemical activation, emerges as an intriguing and booming area. However, its development seriously suffers from the entanglement between the photoelectronic and photothermal effects induced by the decay of plasmons, especially under the influence of applied potential. Herein, using LSPR-mediated CO2 reduction on Ag electrocatalyst as a model system, we quantitatively uncover the dominant photoelectronic effect on CO2 reduction reaction over a wide potential window, in contrast to the leading photothermal effect on H2 evolution reaction at relatively negative potentials. The excitation of LSPR selectively enhances the CO faradaic efficiency (17-fold at -0.6 VRHE ) and partial current density (100-fold at -0.6 VRHE ), suppressing the undesired H2 faradaic efficiency. Furthermore, in situ attenuated total reflection-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveals a plasmon-promoted formation of the bridge-bonded CO on Ag surface via a carbonyl-containing C1 intermediate. The present work demonstrates a deep mechanistic understanding of selective regulation of interfacial reactions by coupling plasmons and electrochemistry.

Hyphenated DEMS and ATR-SEIRAS techniques for in situ multidimensional analysis of lithium-ion batteries and beyond.

A wide spectrum of state-of-the-art characterization techniques have been devised to monitor the electrode-electrolyte interface that dictates the performance of electrochemical devices. However, coupling multiple characterization techniques to realize in situ multidimensional analysis of electrochemical interfaces remains a challenge. Herein, we presented a hyphenated differential electrochemical mass spectrometry and attenuated total reflection surface enhanced infrared absorption spectroscopy analytical method via a specially designed electrochemical cell that enables a simultaneous detection of deposited and volatile interface species under electrochemical reaction conditions, especially suitable for non-aqueous, electrolyte-based energy devices. As a proof of concept, we demonstrated the capability of the homemade setup and obtained the valuable reaction mechanisms, by taking the tantalizing reactions in non-aqueous lithium-ion batteries (i.e., oxidation and reduction processes of carbonate-based electrolytes on Li1+xNi0.8Mn0.1Co0.1O2 and graphite surfaces) and lithium-oxygen batteries (i.e., reversibility of the oxygen reaction) as model reactions. Overall, we believe that the coupled and complementary techniques reported here will provide important insights into the interfacial electrochemistry of energy storage materials (i.e., in situ, multi-dimensional information in one single experiment) and generate much interest in the electrochemistry community and beyond.

Electrolyte-Layer-Tunable ATR-SEIRAS for Simultaneous Detection of Adsorbed and Dissolved Species in Electrochemistry.

A balanced detection of both adsorbates and dissolved species is very important for the clarification of the electrochemical reaction mechanism yet remains a major challenge for different modes of electrochemical infrared (IR) spectroscopy. Among others, conventional attenuated total reflection-surface-enhanced IR absorption spectroscopy (ATR-SEIRAS) is far less sensitive to low-concentration solution species than to surface species. We report herein an electrochemical wide-frequency ATR-SEIRAS with a novel thin-layer flow cell design, fulfilling the simultaneous detection of the variations of surface and solution species. This setup consists of a silicon wafer (with one side micromachined and the other side metallized), a thin-layer electrolyte structure with tunable thickness and flow rate, and a tilt-correction system based on laser collimation, enabling a well-controlled mass transport within the electrolyte layer and the spectral differentiation of solution species from adsorbates. Using acidic methanol oxidation on a Pt film electrode as a model system, besides SEIRA bands for adsorbed CO and formate intermediates, IR spectral signals for dissolved products CO2, formic acid, and methyl formate can be readily identified for a quiescent electrolyte layer of ∼20 µm, which are otherwise undetected with conventional ATR-SEIRAS, as indicated by the trend of spectral features with increasing thickness or flow rate.

The severity of portal hypertension by a non-invasive assessment: acoustic structure quantification analysis of liver parenchyma.

BACKGROUND: Acoustic structure quantification (ASQ) has been applied to evaluate liver histologic changes by analyzing the speckle pattern seen on B-mode ultrasound. We aimed to assess the severity of portal hypertension (PHT) through hepatic ultrasonography. METHODS: Sixty patients diagnosed with PHT and underwent surgical treatment with portosystemic shunts were enrolled. Portal pressure (PP) was measured intraoperatively. Patients were divided into subgroups according to the severity of gastroesophageal varices and Child-Pugh class. Three difference ratio (Cm2) values on ASQ histogram mode were analyzed for their relationships with PP, degree of gastroesophageal varices and Child-Pugh liver function. Thirty healthy volunteers matched with the patients for gender and age were enrolled as controls. Comparisons among groups and correlation of the parameters with PP were analyzed. Area under the receive operating characteristic curve was used to evaluate the predicting value of ASQ parameters. RESULTS: In the patients, the ASQ parameters peak Cm2 (Cm2max), mean Cm2 (Cm2mean) and the highest occurred Cm2 value of the obtained red curve (RmaxCm2) were all greatly increased (P < 0.0001, P < 0.0001, P = 0.027). Multiple comparisons indicated that, regardless of Child-Pugh class and degree of gastroesophageal varices, the patients had significantly increased Cm2max and Cm2mean compared with the controls (all P < 0.0001). No differences among subgroups were observed. Cm2max was significantly statistically correlated with PP (r = 0.3505, P < 0.01), degree of varices (r = 0.4998, P < 0.0001). Youden's index for Cm2max with a cut-off value of 140.3 for predicting the presence of PHT, gastroesophageal varices and liver function equal to or worse than Child-Pugh class B were 0.8, 0.91 and 0.84, respectively. CONCLUSIONS: ASQ analysis of ultrasonographic images may have a role in the evaluation of the severity of PHT by detecting liver histologic changes in the speckle pattern caused by cirrhosis.

Preliminary study of carotid variables under ultrasound analysis as predictors for the risk of coronary arterial atherosclerosis.

BACKGROUND: Carotid atherosclerosis by ultrasound scanning can be considered as an ideal window to reflect systemic artery atherosclerosis, which has aroused wide concern for predicting the severity of coronary artery atherosclerosis clinically. Ultrasound radio frequency (RF) data technology has enabled us to evaluate the carotid structure and elastic function precisely, for predicting the severity of coronary artery atherosclerosis. METHODS: Patients with suspected coronary artery disease (CAD) underwent coronary angiography and were assigned to four groups according to whether atherosclerotic plaque was found or not and it caused stenosis. Carotid artery intima-media thickness (IMT) and arterial stiffness were investigated by quality intima-media thickness (QIMT) and quality arterial stiffness (QAS) techniques during ultrasound scanning. Univariable and multivariable modeling were used to investigate correlations of carotid parameters to coronary artery atherosclerosis. Receive operating characteristic (ROC) curves were used to evaluate diagnostic performance of these ultrasound variables. RESULTS: Carotid IMT and stiffness variables pulse wave velocity (PWV), α, ß and compliance coefficient (CC) were statistically different between every two-group's comparisons. IMT correlated with stiffness variables significantly with r = 0.70, 0.77, 0.63, and -0.39, respectively. All variables correlated with the severity of coronary atherosclerosis with the odd ratio (OR) of 1.73, 1.67, 1.19, 1.23, and 0.56 accordingly as IMT, PWV, α, ß and CC were concerned. The AUC of IMT, PWV, α, ß and CC were 0.9257, 0.8910, 0.8016, 0.9383, 0.8581 with correctly classified rate of 88.16%, 83.77%, 78.07%, 86.84%, and 81.58%, respectively. CONCLUSIONS: Carotid artery IMT and stiffness variable PWV, α, ß and CC presented favorable predicting and differentiating values for patients with coronary atherosclerosis of different severity.

Steering the Glycerol Electro-Reforming Selectivity via Cation-Intermediate Interactions.

Electro-reforming of renewable biomass resources is an alternative technology for sustainable pure H2 production. Herein, we discovered an unconventional cation effect on the concurrent formate and H2 production via glycerol electro-reforming. In stark contrast to the cation effect via forming double layers in cathodic reactions, residual cations at the anode were discovered to interact with the glycerol oxidation intermediates to steer its product selectivity. Through a combination of product analysis, transient kinetics, crown ether trapping experiments, in situ IRRAS and DFT calculations, the aldehyde intermediates were discovered to be stabilized by the Li+ cations to favor the non-oxidative C-C cleavage for formate production. The maximal formate efficiency could reach 81.3 % under ≈60 mA cm-2 in LiOH. This work emphasizes the significance of engineering the microenvironment at the electrode-electrolyte interface for efficient electrolytic processes.

Lipidomics reveals the dynamics of lipid profile altered by omega-3 polyunsaturated fatty acid supplementation in healthy people.

Glycerophospholipids (GPs) and sphingolipids (SPs) are important lipid components in the body and play biological functions. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are important nutrients, and their supplements are commonly used for preventing some diseases. However, the effect of n-3 PUFAs on the human glycerophospholipidome and sphingolipidome is unclear. We used targeted lipidomics to study the GP and SP profile of healthy individuals after supplementation with n-3 PUFAs for 3, 7, 14 and 21 days. Fuzzy c-means clustering was used to cluster the lipid species into six classes reflecting different changed-content patterns after n-3 PUFA supplementation. Among the species with significantly changed content, lysophospholipids were the most sensitive; their content started to increase on day 3. The content of phosphatidylserines increased at a later stage. The content of most of the phosphatidylcholines and alkylphosphatidylcholines decreased on day 21. A correlation network analysis of lipid species suggested that some enzymes involved in the metabolism of lysophospholipids and phosphatidylserines were regulated by n-3 PUFAs. Levels of creatine kinase-MB (CK-MB), urea, glucose, triglycerides and total bilirubin were altered by n-3 PUFA at 21 days. Correlation analysis revealed that the level of CK-MB was negatively correlated with those of species in lysophosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine and phosphatidylserine classes, which were increased by n-3 PUFA supplementation. With the analysis in this work, we demonstrated the regular pattern of n-3 PUFAs on GP and SP metabolism, which provides a pharmacological basis for n-3 PUFAs for clinical application.

Interfacial Structure of Water as a New Descriptor of the Hydrogen Evolution Reaction.

Driven by the persisting poor understanding of the sluggish kinetics of the hydrogen evolution reaction (HER) on Pt in alkaline media, a direct correlation of the interfacial water structure and activity is still yet to be established. Herein, using Pt and Pt-Ni nanoparticles we first demonstrate a strong dependence of the proton donor structure on the HER activity and pH. The structure of the first layer changes from the proton acceptors to the donors with increasing pH. In the base, the reactivity of the interfacial water varied its structure, and the activation energies of water dissociation increased in the sequence: the dangling O-H bonds < the trihedrally coordinated water < the tetrahedrally coordinated water. Moreover, optimizing the adsorption of H and OH intermediates can re-orientate the interfacial water molecules with their H atoms pointing towards the electrode surface, thereby enhancing the kinetics of HER. Our results clarified the dynamic role of the water structure at the electrode-electrolyte interface during HER and the design of highly efficient HER catalysts.

Nature of Oxygen-Containing Groups on Carbon for High-Efficiency Electrocatalytic CO2 Reduction Reaction.

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.

Exploiting the Surface-Enhanced IR Absorption Effect in the Photothermally Induced Resonance AFM-IR Technique toward Nanoscale Chemical Analysis.

The photothermally induced resonance AFM-IR technique (denoted as PTIR) is a promising and still developing analytical method that can provide nanoscale chemical and topographical information. Herein, by taking advantage of a customized PTIR system with either top-down or bottom-up incidence mode for a quantum cascade laser (QCL), we explore how the surface-enhanced IR absorption (SEIRA) effect due to the Au-coated AFM tip and/or substrate may affect the PTIR signals from 25 to 580 nm thick p-nitrobenzoic acid (PNBA) samples, as a function of sample thickness, incidence mode, laser polarization, and Au film morphology. By analysis of the νas(NO2) band intensity, it is revealed that the SEIRA effect may increase the PTIR signals by 1.5-8.3 times, with that from the Au-coated substrate being greater than that from the Au-coated tip. Nevertheless, the overall PTIR signal goes up monotonically over the entire thickness range for the top-down incidence mode, while it increases and then decreases with the sample thickness for the bottom-up incidence mode. The p-polarized laser enhances the PTIR signal more than does the s-polarized laser, especially on the Au-coated substrate. The significant loss of the PTIR signal of a PNBA sample corroborates the substantial loss of the SEIRA effect of an annealed Au film. The present work may promote the application of the SEIRA effect to the PTIR technique and provides hints for developing the PTIR technique into a more versatile analytical tool.

Boosting Formate Production in Electrocatalytic CO2 Reduction over Wide Potential Window on Pd Surfaces.

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.

Direct Observation on Reaction Intermediates and the Role of Bicarbonate Anions in CO2 Electrochemical Reduction Reaction on Cu Surfaces.

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.

[Evaluation of Measures and Achievements of Malaria Control in Tengchong City, Yunnan Province during 2010-2015].

Objective: To evaluate the measures and achievements of malaria control in Tengchong City during 2010-2015. Methods: The malaria control information on epidemiology, foci disposal, blood detection of febrile patients, and medical treatment during 2010-2015 in Tengchong City was collected and analyzed using Microsoft Excel 2010. Results: In 2010-2015, 1 654 malaria cases were reported in Tengchong City, including 18 indigenous cases, 22 domestically mobile cases, and 1 614 imported cases from abroad, of whom 1 584 cases （98.1%） were imported from Myanmar. Most of the cases were vivax malaria（76.2%, 1 261/1 654）. No indigenous malaria cases were reported from 2013 to 2015. Blood test was conducted for 80 655 febrile patients, with a positive detection rate of 2.1%（1 654/80 655）. The positive detection rate was highest in 2010 （2.8%, 700/24 861）, lowest in 2011（1.4%, 341/23 623）, and decreased from 2012 to 2015. In addition, 1 654 cases were directly reported through online system. The 24-h case report rate during 2013-2015 was 100%. A total of 1 191 cases were investigated. The 3-day case investigation rate during 2013-2015 was 100%. A total of 1 351 endemic foci were investigated. The 7-day foci disposal rate during 2014-2015 was 100%. Conclusion: No indigenous transmission has been reported for three years in Tengchong City. However, the imported malaria remains an important problem.

B-doped Pd catalyst: boosting room-temperature hydrogen production from formic acid-formate solutions.

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.

Electrocatalysis of formic acid on palladium and platinum surfaces: from fundamental mechanisms to fuel cell applications.

Formic acid as a natural biomass and a CO2 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.

Uncovering the Dissociative Adsorption of the Leveler Janus Green B on Cu Electrodes at the Molecular Level.

The interfacial adsorption structure of an organic leveler decides its functionality in Cu interconnect electroplating and is yet far from clear. In this work, in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and electrochemical quartz crystal microbalance (EQCM) in conjunction with density functional theory (DFT) calculations are applied to unravel the interfacial adsorption of the classic dye leveler Janus Green B (JGB) at a Cu electrode and understand its polarization property against Cu electrodeposition from an adsorption structure perspective. ATR-SEIRAS measurements and DFT calculations reveal that the N=N bond of the JGB molecule splits via reductive hydrogenation, forming two fragments of contrasting adsorption configurations. JGB exhibits the strongest inhibition effect on Cu deposition among all the tested additives including individual and mixed fragments, due to the highest coverage of organic adsorbates from JGB dissociation, as measured by EQCM. This work highlights the advantage of surface sensitive analytical tools in understanding the structure-performance of levelers.

Lutetium-Induced Ultrafine PtRu Nanoclusters with a High Electrochemical Surface Area for Direct Methanol Fuel Cells at Alleviated Temperatures.

PtRu alloys have been recognized as the state-of-the-art catalysts for the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). However, their applications in DMFCs are still less efficient in terms of both catalytic activity and durability. Rare earth (RE) metals have been recognized as attractive elements to tune the catalytic activity, while it is still a world-class challenge to synthesize well-dispersed Pt-RE alloys. Herein, we developed a novel hydrogen-assisted magnesiothermic reduction strategy to prepare a highly dispersed carbon-supported lutetium-doped PtRu catalyst with ultrafine nanoclusters and atomically dispersed Ru sites. The PtRuLu catalyst shows an outstanding high electrochemical surface area (ECSA) of 239.0 m2 gPt-1 and delivers an optimized MOR mass activity and specific activity of 632.5 mA mgPt-1 and 26 A cmPt-2 at 0.4 V vs saturated calomel electrode (SCE), which are 3.6 and 3.5 times of commercial PtRu-JM and an order higher than PtLu, respectively. These novel catalysts have been demonstrated in a high-temperature direct methanol fuel cell running in a temperature range of 180-240 °C, achieving a maximum power density of 314.3 mW cm-2. The AC-STEM imaging, in situ ATR-IR spectroscopy, and DFT calculations disclose that the high performance is resulted from the highly dispersed PtRuLu nanoclusters and the synergistic effect of the atomically dispersed Ru sites with PtRuLu nanoclusters, which significantly reduces the CO* intermediates coverage due to the promoted water activation to form the OH* to facilitate the CO* removal.

Infrared spectroelectrochemical study of dissociation and oxidation of methanol at a palladium electrode in alkaline solution.

The dissociative adsorption and electrooxidation of CH(3)OH at a Pd electrode in alkaline solution are investigated by using in situ infrared spectroscopy with both internal and external reflection modes. The former (ATR-SEIRAS) has a higher sensitivity of detecting surface species, and the latter (IRAS) can easily detect dissolved species trapped in a thin-layer-structured electrolyte. Real-time ATR-SEIRAS measurement indicates that CH(3)OH dissociates to CO(ad) species at a Pd electrode accompanied by a "dip" at open circuit potential, whereas deuterium-replaced CH(3)OH doesn't, suggesting that the breaking of the C-H bond is the rate-limiting step for the dissociative adsorption of CH(3)OH. Potential-dependent ATR-SEIRAS and IRAS measurements indicate that CH(3)OH is electrooxidized to formate and/or (bi)carbonate, the relative concentrations of which depend on the potential applied. Specifically, at potentials negative of ca. -0.15 V (vs Ag/AgCl), formate is the predominant product and (bi)carbonate (or CO(2) in the thin-layer structure of IRAS) is more favorable at potentials from -0.15 to 0.10 V. Further oxidation of the CO(ad) intermediate species arising from CH(3)OH dissociation is involved in forming (bi)carbonate at potentials above -0.15 V. Although the partial transformation from interfacial formate to (bi)carbonate may be justified, no bridge-bonded formate species can be detected over the potential range under investigation.