Undoped ruthenium oxide as a stable catalyst for the acidic oxygen evolution reaction.

Reducing green hydrogen production cost is critical for its widespread application. Proton-exchange-membrane water electrolyzers are among the most promising technologies, and significant research has been focused on developing more active, durable, and cost-effective catalysts to replace expensive iridium in the anode. Ruthenium oxide is a leading alternative while its stability is inadequate.

Dry-Solid-Electrochemical Synthesis: A General Method for Large Scale Synthesis of Single-Atom Catalysts with High Metal loadings.

Single-atom catalysts (SACs) with high metal loadings are highly desirable but still challenging for large scale synthesis. Here we report a new technique named as dry-solid-electrochemical synthesis (DSES) for a general large-scale synthesis of SACs with high metal loadings in an energy-conservation and environment-friendly way. With it, a series of pure carbon-supported metal SACs (Platinum up to 35.

Towards bridging thermo/electrocatalytic CO oxidation: from nanoparticles to single atoms.

Proton exchange membrane fuel cells (PEMFCs), as a feasible alternative to replace the traditional fossil fuel-based energy converter, contribute significantly to the global sustainability agenda. At the PEMFC anode, given the high exchange current density, Pt/C is deemed the catalyst-of-choice to ensure that the hydrogen oxidation reaction (HOR) occurs at a sufficiently fast pace. The high performance of Pt/C, however, can only be achieved under the premise that high purity hydrogen is used.

Monosymmetric Fe-N sites enabling durable proton exchange membrane fuel cell cathode by chemical vapor modification.

The limited durability of metal-nitrogen-carbon electrocatalysts severely restricts their applicability for the oxygen reduction reaction in proton exchange membrane fuel cells. In this study, we employ the chemical vapor modification method to alter the configuration of active sites from FeN to the stable monosymmetric FeN+N', along with enhancing the degree of graphitization in the carbon substrate. This improvement effectively addresses the challenges associated with Fe active center leaching caused by N-group protonation and free radicals attack due to the 2-electron oxygen reduction reaction.

Single atom sites as CO scavenger to allow for crude hydrogen usage in PEMFC.

Nanosized Pt catalysts are the catalyst-of-choice for proton exchange membrane fuel cell (PEMFC) anode, but are limited by their extreme sensitivity to CO in parts per million (ppm) level, thereby making the use of ultrapure H a prerequisite to ensure acceptable performance. Herein, we confront the CO poisoning issue by bringing the Ir/Rh single atom sites to synergistically working with their metallic counterparts. In presence of 1000 ppm CO, the catalyst represents not only undisturbed H oxidation reaction (HOR) catalytic behavior in electrochemical cell, but also unparalleled peak power density at 643 mW cm in single cell, 27-fold in mass activity of the best PtRu/C catalysts available.

Operando formation of highly efficient electrocatalysts induced by heteroatom leaching.

Heterogeneous nano-electrocatalysts doped with nonmetal atoms have been studied extensively based on the so-called dopant-based active sites, while little attention has been paid to the stability of these dopants under working conditions. In this work, we reveal significantly, when the redox working potential is too low negatively or too high positively, the active sites based on these dopants actually tend to collapse. It means that some previously observed "remarkable catalytic performance" actually originated from some unknown active sites formed in situ.

Rare Earth Evoked Subsurface Oxygen Species in Platinum Alloy Catalysts Enable Durable Fuel Cells.

Alleviating the degradation issue of Pt based alloy catalysts, thereby simultaneously achieving high mass activity and high durability in proton exchange membrane fuel cells (PEMFCs), is highly challenging. Herein, we provide a new paradigm to address this issue via delaying the place exchange between adsorbed oxygen species and surface Pt atoms, thereby inhibiting Pt dissolution, through introducing rare earth bonded subsurface oxygen atoms. We have succeeded in introducing Gd-O dipoles into Pt Ni via a high temperature entropy-driven process, with direct spectral evidence attained from both soft and hard X-ray absorption spectroscopies.

Intrinsic spin shielding effect in platinum-rare-earth alloy boosts oxygen reduction activity.

Oxygen reduction reactions (ORRs) involve a multistep proton-coupled electron process accompanied by the conversion of the apodictic spin configuration. Understanding the role of spin configurations of metals in the adsorption and desorption of oxygen intermediates during ORRs is critical for the design of efficient ORR catalysts. Herein, a platinum-rare-earth-metal-based alloy catalyst, PtGd, is introduced to reveal the role of spin configurations in the catalytic activity of materials.

Regulating the MXene-Zinc Interfacial Structure toward a Highly Revisable Metal Anode of Zinc-Air Batteries.

Rechargeable aqueous Zn-air batteries have been regarded as one of the most promising systems for flexible energy storage devices due to their high specific energy, safety, and cost effectiveness. However, Zn metal anodes exposed to strong alkaline electrolytes suffer from several issues such as corrosion, dissolution, and passivation, resulting in extremely poor cycle reversibility. Motivated by this challenge, we herein strategically design an MXene/Zn metal anode interfacial structure with single/few-layer TiCT MXene as a protective layer.

Customized reaction route for ruthenium oxide towards stabilized water oxidation in high-performance PEM electrolyzers.

The poor stability of Ru-based acidic oxygen evolution (OER) electrocatalysts has greatly hampered their application in polymer electrolyte membrane electrolyzers (PEMWEs). Traditional understanding of performance degradation centered on influence of bias fails in describing the stability trend, calling for deep dive into the essential origin of inactivation. Here we uncover the decisive role of reaction route (including catalytic mechanism and intermediates binding strength) on operational stability of Ru-based catalysts.

Challenges and Strategies of Anion Exchange Membranes in Hydrogen-electricity Energy Conversion Devices.

Alkaline hydrogen-electricity energy conversion technologies, involving anion exchange membrane fuel cells (AEMFCs) and anion exchange membrane water electrolyzers (AEMWEs) are more appealing than the acidic counterparts due to the elimination of precious metal catalysts. However, the physicochemical properties of anion exchange membrane (AEMs), i.e.

Co-based Catalysts for Selective H O Electroproduction via 2-electron Oxygen Reduction Reaction.

Electrochemical production of hydrogen peroxide (H O ) via two-electron oxygen reduction reaction (ORR) process is emerging as a promising alternative method to the conventional anthraquinone process. To realize high-efficiency H O electrosynthesis, robust and low cost electrocatalysts have been intensively pursued, among which Co-based catalysts attract particular research interests due to the earth-abundance and high selectivity. Here, we provide a comprehensive review on the advancement of Co-based electrocatalyst for H O electroproduction.

Enhanced Acidic Water Oxidation by Dynamic Migration of Oxygen Species at the Ir/Nb O Catalyst/Support Interfaces.

Catalyst/support interaction plays a vital role in catalysis towards acidic oxygen evolution (OER), and the performance reinforcement is currently interpreted by either strain or electron donation effect. We herein report that these views are insufficient, where the dynamic evolution of the interface under potential bias must be considered. Taking Nb O supported iridium (Ir/Nb O ) as a model catalyst, we uncovered the dynamic migration of oxygen species between IrO and Nb O during OER.

High-Performance RuO Catalyst with Advanced Mesoporous Structure for Oxygen Evolution Reaction.

Polymer electrolyte membrane water electrolysis (PEMWE) is regarded as one of the most important cornerstone technologies in the upcoming hydrogen society. However, one of the major problems it encounters is its slow oxygen evolution kinetics, which necessitates the use of large amounts of precious metal catalysts to ensure a satisfactory reaction rate. Herein, we have prepared a series of RuO with porous structures and ultrahigh Ru utilization toward the oxygen evolution reaction.

Nickel Phosphide Coated with Ultrathin Nitrogen-Doped Carbon Shell as a Highly Durable and Active Catalyst towards Hydrogen Evolution Reaction.

Developing non-precious metal catalysts towards hydrogen evolution reaction (HER) is of both high scientific and technical importance for the widespread application of water electrolysis. Herein, Ni P nanoparticles coated with a ultrathin N-doped carbon shell were prepared as a highly efficient HER catalyst. Ni P@CN exhibits both enhanced catalytic activity and durability in comparison with the carbon-supported Ni P counterpart, and represents 100% faradaic yield for HER in an acidic medium.

Description of three new species of Gomphomastacinae (Orthoptera: Eumastacoidea) from the east of Qinghai-Tibet plateau, China.

The grasshopper Subfamily Gomphomastacinae (Orthoptera: Acridoidea: Eumastacidae) is widely distributed in the Qinghai-Tibetan Plateau and Central Asia. This paper describes three new species: Ptygomastax nihilsulcus Ge, sp. nov.

CO-Tolerant PEMFC Anodes Enabled by Synergistic Catalysis between Iridium Single-Atom Sites and Nanoparticles.

Proton-exchange membrane fuel cells (PEMFCs) are limited by their extreme sensitivity to trace-level CO impurities, thus setting a strict requirement for H purity and excluding the possibility to directly use cheap crude hydrogen as fuel. Herein, we report a proof-of-concept study, in which a novel catalyst comprising both Ir particles and Ir single-atom sites (Ir @Ir -N-C) addresses the CO poisoning issue. The Ir single-atom sites are found not only to be good CO oxidizing sites, but also excel in scavenging the CO molecules adsorbed on Ir particles in close proximity, thereby enabling the Ir particles to reserve partial active sites towards H oxidation.

Proton exchange membrane fuel cells powered with both CO and H.

The CO electrooxidation is long considered invincible in the proton exchange membrane fuel cell (PEMFC), where even a trace level of CO in H seriously poisons the anode catalysts and leads to huge performance decay. Here, we describe a class of atomically dispersed IrRu-N-C anode catalysts capable of oxidizing CO, H, or a combination of the two. With a small amount of metal (24 μg⋅cm) used in the anode, the H fuel cell performs its peak power density at 1.

Carbon monoxide powered fuel cell towards H-onboard purification.

Proton exchange membrane fuel cells (PEMFCs) suffer extreme CO poisoning even at PPM level (<10 ppm), owning to the preferential CO adsorption and the consequential blockage of the catalyst surface. Herein, however, we report that CO itself can become an easily convertible fuel in PEMFC using atomically dispersed Rh catalysts (Rh-N-C). With CO to CO conversion initiates at 0 V, pure CO powered fuel cell attains unprecedented power density at 236 mW cm, with maximum CO turnover frequency (64.

Preferentially Engineering FeN Edge Sites onto Graphitic Nanosheets for Highly Active and Durable Oxygen Electrocatalysis in Rechargeable Zn-Air Batteries.

Single-atom FeN sites at the edges of carbon substrates are considered more active for oxygen electrocatalysis than those in plane; however, the conventional high-temperature pyrolysis process does not allow for precisely engineering the location of the active site down to atomic level. Enlightened by theoretical prediction, herein, a self-sacrificed templating approach is developed to obtain edge-enriched FeN sites integrated in the highly graphitic nanosheet architecture. The in situ formed Fe clusters are intentionally introduced to catalyze the growth of graphitic carbon, induce porous structure formation, and most importantly, facilitate the preferential anchoring of FeN to its close approximation.

Construction and Regulation of a Surface Protophilic Environment to Enhance Oxygen Reduction Reaction Electrocatalytic Activity.

Pyrolytic transition metal nitrogen-carbon (M-N/C) materials are considered as the most promising alternatives for platinum-based catalysts toward oxygen reduction reaction (ORR). As the proton-coupled electron transfer step in ORR has been proven to be a rate-determining step in the M-N/C catalysts, we envisaged that building a protophilic surface might be helpful to enhance the ORR activity. Herein, a polyaniline decoration strategy was put forward and realized to confer the Fe-N/C catalyst with a surface protophilic environment.

Fundamental understanding of the acidic oxygen evolution reaction: mechanism study and state-of-the-art catalysts.

The oxygen evolution reaction (OER), as the anodic reaction of water electrolysis (WE), suffers greatly from low reaction kinetics and thereby hampers the large-scale application of WE. Seeking active, stable, and cost-effective OER catalysts in acidic media is therefore of great significance. In this perspective, studying the reaction mechanism and exploiting advanced anode catalysts are of equal importance, where the former provides guidance for material structural engineering towards a better catalytic activity.

Bridge Bonded Oxygen Ligands between Approximated FeN Sites Confer Catalysts with High ORR Performance.

The applications of the most promising Fe-N-C catalysts are prohibited by their limited intrinsic activities. Manipulating the Fe energy level through anchoring electron-withdrawing ligands is found effective in boosting the catalytic performance. However, such regulation remains elusive as the ligands are only uncontrollably introduced oweing to their energetically unstable nature.

Reactant friendly hydrogen evolution interface based on di-anionic MoS surface.

Engineering the reaction interface to preferentially attract reactants to inner Helmholtz plane is highly desirable for kinetic advancement of most electro-catalysis processes, including hydrogen evolution reaction (HER). This, however, has rarely been achieved due to the inherent complexity for precise surface manipulation down to molecule level. Here, we build a MoS di-anionic surface with controlled molecular substitution of S sites by -OH.

Engineering Energy Level of Metal Center: Ru Single-Atom Site for Efficient and Durable Oxygen Reduction Catalysis.

Emerging as a new frontier in heterogeneous catalysis, single-atom site catalysts (SSCs) have sparked enormous attention and bring about new opportunities to oxygen reduction electrocatalysis. Despite considerable progress achieved recently, most of the reported SSCs suffer from either insufficient activity or unsatisfactory stability, which severely retards their practical application. Here, we demonstrate a novel Ru-SSC with appropriate adsorption free energy of OH* (Δ) to confer excellent activity and low Fenton reactivity to maintain long-term stability.