The sluggish kinetics of oxygen evolution reaction (OER) is the main bottleneck for the electrocatalytic water splitting to produce hydrogen (H2), and the by‐product is worthless O2. Therefore, ...designing a thermodynamically favorable oxidation reaction to replace OER and coupling with value‐added product generation on the anode is of significance for boosting H2 generation under low electrolysis voltage. Herein, cobalt hydroxide@hydroxysulfide nanosheets on carbon paper (Co(OH)2@HOS/CP) are synthesized as bifunctional electrocatalysts to facilitate H2 production and convert methanol to valuable formate simultaneously. Benefiting from the influences/changes on the composition, surface properties, electronic structure, and chemistry of Co(OH)2, the as‐obtained electrodes exhibit very high selectivity for methanol to value‐added formate oxidation (MFO) and boost electrocatalytic performance with low overpotential of 155 mV for MFO and 148 mV for hydrogen evolution reaction at a current density of 10 mA cm−2. Furthermore, the integrated two‐electrode electrolyzer drives 10 mA cm−2 at a cell voltage of 1.497 V with united 100% Faradaic efficiency for anodic and cathodic reaction and continuous 20 h of operation without obvious decay. The electrocatalytic hydrogen production with the assistance of alternative oxidation by the robust electrocatalyst can be further used to realize the upgrading of other organic molecules with less energy consumption.
New cobalt hydroxide@hydroxysulfide nanosheet electrocatalysts are developed to boost hydrogen fuel generation by coupling with selective oxidation of methanol to a value‐added formate. As a result, the electrolysis voltage is reduced to 1.497 V at a current density of 10 mA cm−2 and the Faradaic efficiencies are closed to 100% at the anode and cathode.
Constructing monodispersed metal sites in heterocatalysis is an efficient strategy to boost their catalytic performance. Herein, a new strategy using monodispersed metal sites to tailor Pt‐based ...nanocatalysts is addressed by engineering unconventional p–d orbital hybridization. Thus, monodispersed Ga on Pt3Mn nanocrystals (Ga‐O‐Pt3Mn) with high‐indexed facets was constructed for the first time to drive ethanol electrooxidation reaction (EOR). Strikingly, the Ga‐O‐Pt3Mn nanocatalyst shows an enhanced EOR performance with achieving 8.41 times of specific activity than that of Pt/C. The electrochemical in situ Fourier transform infrared spectroscopy results and theoretical calculations disclose that the Ga‐O‐Pt3Mn nanocatalyst featuring an unconventional p–d orbital hybridization not only promote the C−C bond‐breaking and rapid oxidation of ‐OH of ethanol, but also inhibit the generation of poisonous CO intermediate species. This work discloses a promising strategy to construct a novel nanocatalysts tailored by monodispersed metal site as efficient fuel cell catalysts.
The monodispersed Ga site tailored Pt3Mn nanocatalyst based on high‐indexed facets was constructed and shows excellent EOR performance with high activity and selectivity towards the C2 reaction pathway, which was attributed to the unconventional p–d orbital hybridization and atomic‐level interface synergy.
Electro‐oxidative organic upgrading, as an ideal alternative to sluggish oxygen evolution reaction (OER) performance, can effectively decrease energy consumption to boost hydrogen evolution reaction ...(HER) performance. However, developing highly active electrocatalysts for long‐term durable organic upgrading with high selectivity at large and steady current density remains challenging. Herein, hollow NiSe nanocrystals heterogenized with carbon nanotubes (h‐NiSe/CNTs) are fabricated via a facile one‐pot approach. The highly dispersed h‐NiSe/CNTs 3D network can efficiently facilitate rapid mass/electron diffusion, thus achieving highly active and long‐term stable electrocatalysis for catalyzing methanol to value‐added formate at high and steady current density (≈345 mA cm−2) with high Faradaic efficiency (>95%). This reaction replaces sluggish OER performance to reduce the energy consumption for boosting H2 generation by six times. The critical active species and methanol activation mechanism are systematically studied using X‐ray photoelectron spectroscopy, X‐ray absorption fine structure analysis, in situ Raman, and density functional theory calculations, indicating that the non‐ignorable SeOx collaborated with in situ formed NiOOH species can synergistically modulate the d band center to achieve an optimal adsorption for methanol selective oxidation and suppress the further oxidation to CO2, thus leading to active and stable electrolysis for producing value‐added formate with high selectivity and co‐generating H2 with less energy consumption.
Hollow NiSe nanocrystals/carbon nanotubes nanoheterostructures are synthesized as highly active and durable electrocatalysts for long‐term methanol selective upgrading conversion to value‐added formate at large and steady current density (≈345 mA cm−2) with a high Faradaic efficiency (>95%), simultaneously replacing sluggish OER performance to boost H2 generation with lower energy costs.
Electrocatalytic CN coupling between carbon dioxide and nitrate has emerged to meet the comprehensive demands of carbon footprint closing, valorization of waste, and sustainable manufacture of urea. ...However, the identification of catalytic active sites and the design of efficient electrocatalysts remain a challenge. Herein, the synthesis of urea catalyzed by copper single atoms decorated on a CeO2 support (denoted as Cu1–CeO2) is reported. The catalyst exhibits an average urea yield rate of 52.84 mmol h−1 gcat.−1 at −1.6 V versus reversible hydrogen electrode. Operando X‐ray absorption spectra demonstrate the reconstitution of copper single atoms (Cu1) to clusters (Cu4) during electrolysis. These electrochemically reconstituted Cu4 clusters are real active sites for electrocatalytic urea synthesis. Favorable CN coupling reactions and urea formation on Cu4 are validated using operando synchrotron‐radiation Fourier transform infrared spectroscopy and theoretical calculations. Dynamic and reversible transformations of clusters to single‐atom configurations occur when the applied potential is switched to an open‐circuit potential, endowing the catalyst with superior structural and electrochemical stabilities.
Electrocatalytic CN coupling between carbon dioxide and nitrate emerges to meet comprehensive demands of carbon footprint closing, valorization of waste, and sustainable manufacture of urea. Herein, the urea synthesis catalyzed by Cu1–CeO2 is reported. The dynamic reversible reconstitution of the catalyst configuration is monitored using operando X‐ray absorption spectra and the Cu4 clusters are real active sites for electrocatalytic urea synthesis. Transform of clusters back to single‐atom configurations occurs when the applied potential is switched to an open‐circuit potential, endowing the catalyst with superior structural and electrochemical stabilities.
Machine learning (ML) is emerging as a powerful tool for identifying quantitative structure–activity relationships to accelerate electrocatalyst design by learning from historic data without explicit ...programming. The algorithms, data/database, and descriptors are usually the decisive factors for ML and the descriptors play a pivotal role for electrocatalysis as they contain the essence of catalysis from the physicochemical nature. Despite the considerable research efforts regarding electrocatalyst design with ML, the lack of universal selection tactics for descriptors bridging the gap between structures and activity impedes its wider application. A timely summary of the application of ML in electrocatalyst design helps to deepen the understanding of the nature of descriptors and improve the application scope and design efficiency. This review summarizes the geometrical, electronic, and activity descriptors used as input for ML training and predicting to reveal the general rules for their application in the design of electrocatalysts. In response to the challenges of hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, CO2 reduction reaction, and nitrogen reduction reaction, the ML application in these areas is tracked for the progress and prospective changes. Additionally, the potential application of the automated design and discovery are discussed for the other well‐known electrocatalytic processes.
Descriptors play a pivotal role for machine learning (ML)‐assisted electrocatalyst design as they contain the essence of catalysis from the physicochemical nature. This article reviews the progresses and prospectives of the descriptor‐oriented ML application in the design of electrocatalysts for oxygen evolution reaction, oxygen reduction reaction, CO2 reduction reaction, and nitrogen reduction reaction.
Integrating biomass upgrading and hydrogen production in an electrocatalytic system is attractive both environmentally and in terms of sustainability. Conventional electrolyser systems coupling ...anodic biosubstrate electrooxidation with hydrogen evolution reaction usually require electricity input. Herein, we describe the development of an electrocatalytic system for simultaneous biomass upgrading, hydrogen production, and electricity generation. In contrast to conventional furfural electrooxidation, the employed low‐potential furfural oxidation enabled the hydrogen atom of the aldehyde group to be released as gaseous hydrogen at the anode at a low potential of approximately 0 VRHE (vs. RHE). The integrated electrocatalytic system could generate electricity of about 2 kWh per cubic meter of hydrogen produced. This study may provide a transformative technology to convert electrocatalytic biomass upgrading and hydrogen production from a process requiring electricity input into a process to generate electricity.
By coupling anodic low‐potential furfural oxidation with the cathodic oxygen reduction reaction, a multipurpose electrocatalytic system was assembled for biomass upgrading, hydrogen production, and electricity generation. This system could generate about 2 kWh of electricity per cubic meter of H2 produced, instead of requiring electricity input.
Different from graphene with the highly stable sp2‐hybridized carbon atoms, which shows poor controllability for constructing strong interactions between graphene and guest metal, graphdiyne has a ...great potential to be engineered because its high‐reactive acetylene linkages can effectively chelate metal atoms. Herein, a hydrogen‐substituted graphdiyne (HsGDY) supported metal catalyst system through in situ growth of Cu3Pd nanoalloys on HsGDY surface is developed. Benefiting from the strong metal‐chelating ability of acetylenic linkages, Cu3Pd nanoalloys are intimately anchored on HsGDY surface that accordingly creates a strong interaction. The optimal HsGDY‐supported Cu3Pd catalyst (HsGDY/Cu3Pd‐750) exhibits outstanding electrocatalytic activity for the oxygen reduction reaction (ORR) with an admirable half‐wave potential (0.870 V), an impressive kinetic current density at 0.75 V (57.7 mA cm−2) and long‐term stability, far outperforming those of the state‐of‐the‐art Pt/C catalyst (0.859 V and 15.8 mA cm−2). This excellent performance is further highlighted by the Zn–air battery using HsGDY/Cu3Pd‐750 as cathode. Density function theory calculations show that such electrocatalytic performance is attributed to the strong interaction between Cu3Pd and CC bonds of HsGDY, which causes the asymmetric electron distribution on two carbon atoms of CC bond and the strong charge transfer to weaken the shoulder‐to‐shoulder π conjugation, eventually facilitating the ORR process.
A hydrogen‐substituted graphdiyne (HsGDY) supported metal system is successfully developed through in situ growth of Cu3Pd nanoalloy on the surface of HsGDY. The strong HsGDY‐Cu3Pd interaction induced by the unique chelating ability of acetylenic linkages in HsGDY endows the optimally performing catalyst with excellent electrocatalytic oxygen reduction reaction performance.
Electrolytic overall water splitting is a promising approach to produce H2, but its efficiency is severely limited by the sluggish kinetics of the oxygen evolution reaction (OER) and the low activity ...of current electrocatalysts. To solve these problems, in addition to the development of efficient precious‐metal catalysts, an effective strategy is proposed to replace the OER by the selective methanol oxidation reaction. Ni–Co hydroxide NixCo1−x(OH)2 nanoarrays were obtained through a facile hydrothermal treatment as the bifunctional electrocatalysts for the co‐electrolysis of methanol/water to produce H2 and value‐added formate simultaneously. The electrocatalyst could catalyze selective methanol oxidation (≈1.32 V) with a significantly lower energy consumption (≈0.2 V less) than OER. Importantly, methanol was transformed exclusively to value‐added formate with a high Faradaic efficiency (selectivity) close to 100 %. Specifically, a cell voltage of only approximately 1.5 V was required to generate a current density of 10 mA cm−2. Furthermore, the Ni0.33Co0.67(OH)2/Ni foam nanoneedle arrays presented an outstanding stability for overall co‐electrolysis.
Double bubble: A strategy is proposed for the cogeneration of H2 and value‐added formate from the electrolysis of methanol/water by a Ni–Co double hydroxide nanoneedle array bifunctional electrocatalyst.
The Co‐based electrocatalyst is among the most promising candidates for electrochemical oxidation of 5‐hydroxymethylfurfural (HMF). However, the intrinsic active sites and detailed mechanism of this ...catalyst remains unclear. We combine experimental evidence and a theoretical study to show that electrogenerated Co3+ and Co4+ species act as chemical oxidants but with distinct roles in selective HMF oxidation. It is found that Co3+ is only capable of oxidizing formyl group to produce carboxylate while Co4+ is required for the initial oxidation of hydroxyl group with significantly faster kinetics. As a result, the product distribution shows explicit dependence on the Co oxidation states and selective production of 5‐hydroxymethyl‐2‐furancarboxylic acid (HMFCA) and 2,5‐furandicarboxylic acid (FDCA) are achieved by tuning the applied potential. This work offers essential mechanistic insight on Co‐catalyzed organic oxidation reactions and might guide the design of more efficient electrocatalysts.
A detailed mechanism for cobalt‐catalyzed electrochemical 5‐hydroxymethylfurfural (HMF) oxidation is revealed. A combined experimental and theoretical study shows that a Co3+ species is capable of oxidizing the formyl group to produce carboxylate but remains inert towards oxidation of the hydroxyl group. In contrast, a Co4+ species is required for the initial oxidation of the hydroxyl group in HMF.
Mesoporous bismuth nanosheets are prepared through electrochemical transformation of (100)‐facet exposed BiOI. Theoretical modeling and calculations are used to simulate the in situ morphological ...transformation of BiOI into Bi. Mesoporous Bi nanosheets show superior electrochemical CO2 reduction performance. A faradaic efficiency of 95.9 % at −0.77 VRHE for the conversion of CO2 into formic acid, is achieved for the mesoporous Bi nanosheet catalyst compared with 93.8 % at −0.87 VRHE for the smooth Bi nanosheets. Tafel analysis and DFT calculations indicate that the electrochemical CO2 reduction on mesoporous Bi nanosheets is kinetically faster with a higher resistance to H2 generation than that on smooth Bi(001) nanosheets. The CO2‐to‐HCOOH pathway is preferred through formation of an *OCHO intermediate on the (012) and (001) planes of Bi. The mesoporous structure induces a more accessible interaction with CO2, which makes a predominant contribution to the enhanced performance compared with the subsequent CO2 activation on different facets of Bi.
Sheet dreams (are made of this): Mesoporous bismuth nanosheets prepared by electrochemical transformation of (100)‐facet exposed BiOI displayed a faradaic efficiency of 95.9 % at −0.77 VRHE for the conversion of CO2 into formic acid. The mesoporous structure induces better interaction with CO2 and makes a predominant contribution to the enhanced performance compared with the subsequent CO2 activation on different facets of Bi.
