Explore the vast range of titles available.

Developing non-noble catalysts with superior activity and durability for oxygen evolution reaction (OER) in acidic media is paramount for hydrogen production from water. Still, challenges remain due to the inadequate activity and stability of the OER catalyst. Here, we report a cost-effective and stable manganese oxybromide (Mn 7.5 O 10 Br 3 ) catalyst exhibiting an excellent OER activity in acidic electrolytes, with an overpotential of as low as 295 ± 5 mV at a current density of 10 mA cm −2 . Mn 7.5 O 10 Br 3 maintains good stability under operating conditions for at least 500 h. In situ Raman spectroscopy, X ray absorption near edge spectroscopy, and density functional theory calculations confirm that a self-oxidized surface with enhanced electronic transmission capacity forms on Mn 7.5 O 10 Br 3 and is responsible for both the high catalytic activity and long-term stability during catalysis. The development of Mn 7.5 O 10 Br 3 as an OER catalyst provides crucial insights into the design of non-noble metal electrocatalysts for water oxidation. While acidic water splitting offers a renewable means to obtain renewable hydrogen fuel, the catalysts needed to oxidize water often require expensive noble metals. Here, authors show manganese oxyhalides as acidic oxygen evolution electrocatalysts.

Electrochemical conversion of CO 2 to formic acid using Bismuth catalysts is one the most promising pathways for industrialization. However, it is still difficult to achieve high formic acid production at wide voltage intervals and industrial current densities because the Bi catalysts are often poisoned by oxygenated species. Herein, we report a Bi 3 S 2 nanowire-ascorbic acid hybrid catalyst that simultaneously improves formic acid selectivity, activity, and stability at high applied voltages. Specifically, a more than 95% faraday efficiency was achieved for the formate formation over a wide potential range above 1.0 V and at ampere-level current densities. The observed excellent catalytic performance was attributable to a unique reconstruction mechanism to form more defective sites while the ascorbic acid layer further stabilized the defective sites by trapping the poisoning hydroxyl groups. When used in an all-solid-state reactor system, the newly developed catalyst achieved efficient production of pure formic acid over 120 hours at 50 mA cm –2 (200 mA cell current). Achieving high pure formic acid production from CO 2 electroconversion is of high interest yet challenging. Here the authors report vitamin C functionalized Bi 3 S 2 nanowire catalyst to achieve selective, active, and stable formic acid production.

The discovery of Mn-Ca complex in photosystem II stimulates research of manganese-based catalysts for oxygen evolution reaction (OER). However, conventional chemical strategies face challenges in regulating the four electron-proton processes of OER. Herein, we investigate alpha-manganese dioxide (α-MnO 2 ) with typical Mn IV -O-Mn III -H x O motifs as a model for adjusting proton coupling. We reveal that pre-equilibrium proton-coupled redox transition provides an adjustable energy profile for OER, paving the way for in-situ enhancing proton coupling through a new “reagent”— external electric field. Based on the α-MnO 2 single-nanowire device, gate voltage induces a 4-fold increase in OER current density at 1.7 V versus reversible hydrogen electrode. Moreover, the proof-of-principle external electric field-assisted flow cell for water splitting demonstrates a 34% increase in current density and a 44.7 mW/cm² increase in net output power. These findings indicate an in-depth understanding of the role of proton-incorporated redox transition and develop practical approach for high-efficiency electrocatalysis. Manganese complexes have long been utilized by nature to catalyze the oxygen evolution reaction (OER) but mirroring their efficiency in artificial electrochemical systems has proven difficult. This study centers on alpha-manganese dioxide (α-MnO 2 ), which closely mimics natural Mn IV -O-Mn III -H x O motifs, presenting a novel method for manipulating proton coupling within the OER process using an external electric field.

Hitherto, there are almost no reports on the complete reconstruction in hydrogen evolution reaction (HER). Herein, the authors develop a new type of reconfigurable fluoride (such as CoF2) pre‐catalysts, with ultra‐fast and in‐depth self‐reconstruction, substantially promoting HER activity. By experiments and density functional theory (DFT) calculations, the unique surface structure of fluorides, alkaline electrolyte and bias voltage are identified as key factors for complete reconstruction during HER. The enrichment of F atoms on surface of fluorides provides the feasibility of spontaneous and continuous reconstruction. The alkaline electrolyte triggers rapid F− leaching and supplies an immediate complement of OH− to form amorphous α‐Co(OH)2 which rapidly transforms into β‐Co(OH)2. The bias voltage promotes amorphous crystallization and accelerates the reconstruction process. These endow the generation of mono‐component and crystalline β‐Co(OH)2 with a loose and defective structure, leading to an ultra‐low overpotential of 54 mV at 10 mA cm−2 and super long‐term stability exceeding that of Pt/C. Moreover, DFT calculations confirm that F− leaching optimizes hydrogen and water adsorption energies, boosting HER kinetics. Impressively, the self‐reconstruction is also applicable to other non‐noble transition metal fluorides. The work builds the fundamental comprehension of complete self‐reconstruction during HER and provides a new perspective to conceive advanced catalysts. A new type of ultrafast and completely reconfigurable transition metal fluoride pre‐catalysts, including CoF2, NiF2, and FeF3 (H2O)0.33, are found during the alkaline hydrogen evolution reaction process. In terms of CoF2 serving as a representative, its reconstruction mechanism is uncovered.

Non-equilibrium reaction environments offer a route to bypass the thermodynamic constraints that limit conventional nitrogen fixation, yet such conditions remain inaccessible in traditional thermal systems. Here, we show that rapid activation-quenching chemistry inside cavitation bubbles provides a viable non‑equilibrium pathway for nitrogen fixation. The violent collapse of ultrasound-driven bubbles generates an intense temperature pulse that enables direct nitrogen activation and subsequent redox chemistry within a transient gas phase microreactor. Nitrogen-containing products are produced with tuneable rates and selectivity controlled by feed gas composition, cavitation dynamics, and solution properties. Introduced cavitation nuclei lower the cavitation threshold and improve collapse reproducibility, while noble‑gas doping modulates collapse temperatures and shifts nitrate-nitrite distributions through enhancing the involvement of water‑derived species. Isotopic labelling and single‑bubble modelling indicate that nitrogen reaction proceeds predominantly through gas‑phase pathways during collapse, which can be described by a dynamic thermodynamic model within a temperature pulse. These findings establish cavitation‑driven non-equilibrium thermal cycling as a distinct mechanism for nitrogen fixation and underscore the broader potential of transient thermal microenvironments for chemical synthesis. Industrial nitrogen fixation relies on energy-intensive processes. Here, the authors provide mechanistic insights on the transient conditions in acoustic cavitation that activate nitrogen and form nitrogen products in the absence of catalysts.

The oxygen evolution reaction involves complex interplay among electrolyte, solid catalyst, and gas-phase and liquid-phase reactants and products. Monitoring catalysis interfaces between catalyst and electrolyte can provide valuable insights into catalytic ability. But it is a challenging task due to the additive solid supports in traditional measurement. Here we design a nanodevice platform and combine on-chip electrochemical impedance spectroscopy measurement, temporary I-V measurement of an individual nanosheet, and molecular dynamic calculations to provide a direct way for nanoscale catalytic diagnosis. By removing O 2 in electrolyte, a dramatic decrease in Tafel slope of over 20% and early onset potential of 1.344 V vs. reversible hydrogen electrode are achieved. Our studies reveal that O 2 reduces hydroxyl ion density at catalyst interface, resulting in poor kinetics and negative catalytic performance. The obtained in-depth understanding could provide valuable clues for catalysis system design. Our method could also be useful to analyze other catalytic processes. Electrocatalysis offers important opportunities for clean fuel production, but uncovering the chemistry at the electrode surface remains a challenge. Here, the authors exploit a single-nanosheet electrode to perform in-situ measurements of water oxidation electrocatalysis and reveal a crucial interaction with oxygen.

Subtle structural changes during electrochemical processes often relate to the degradation of electrode materials. Characterizing the minute-variations in complementary aspects such as crystal structure, chemical bonds, and electron/ion conductivity will give an in-depth understanding on the reaction mechanism of electrode materials, as well as revealing pathways for optimization. Here, vanadium pentoxide (V 2 O 5 ), a typical cathode material suffering from severe capacity decay during cycling, is characterized by in-situ X-ray diffraction (XRD) and in-situ Raman spectroscopy combined with electrochemical tests. The phase transitions of V 2 O 5 within the 0–1 Li/V ratio are characterized in detail. The V–O and V–V distances became more extended and shrank compared to the original ones after charge/discharge process, respectively. Combined with electrochemical tests, these variations are vital to the crystal structure cracking, which is linked with capacity fading. This work demonstrates that chemical bond changes between the transition metal and oxygen upon cycling serve as the origin of the capacity fading.

The catalytic decomposition of ammonia under mild conditions is a promising route for green hydrogen production. However, conventional dissociative ammonia decomposition pathways over metal sites are suffering from the Brønsted−Evans−Polanyi (BEP) constraint which establishes an inverse correlation between atomic N binding energy and the N-H bond dissociation energy. Herein, we report a ruthenium-supported nitrogen-doped cerium oxide (Ru/N-CeO 2 ) catalyst that breaks this limitation and exhibits significantly enhanced catalytic activity compared to its undoped counterpart. Furthermore, we reveal that N dopants can act as independent active sites, enabling an associative mechanism distinct from the conventional Ru-driven pathway. Comprehensive isotopic labelling experiments together with computational techniques elucidate the reaction mechanism over the N site and reveal a distinct correlation between the location of the active site and catalytic activity. The proximal N site exhibits the highest activity, challenging the conventional view that activity is dominated by metal–support interfacial sites. While N doping is a commonly used approach for surface modification, our findings show that it can also alter the reaction mechanism by introducing new active sites. These insights offer valuable guidance for the rational design of catalytic supports in ammonia decomposition and open new directions for catalytic systems limited by scaling relationships in heterogenous catalysis.

Advances in electrochemical energy storage technologies drive the need for battery safety performance and miniaturization, which calls for the easily processable polymer electrolytes suitable for on-chip microbattery technology. However, the low ionic conductivity of polymer electrolytes and poor-patternable capabilities hinder their application in microdevices. Herein, we modified SU-8, as the matrix material, by poly(ethylene oxide) (PEO) with lithium salts to obtain a patternable lithium-ion polymer electrolyte. Due to the highly amorphous state and more Li-ion transport pathways through blending effect and the increase in number of epoxides, the ionic conductivity of achieved sample is increased by an order of magnitude to 2.9 × 10 −4 S·cm −1 in comparison with the SU-8 sample at 50 °C. The modified SU-8 exhibits good thermal stability (> 150 °C), mechanical properties (elastic modulus of 1.52 GPa), as well as an electrochemical window of 4.3 V. Half-cell and microdevice were fabricated and tested to verify the possibility of the micro-sized on-chip battery. All of these results demonstrate a promising strategy for the integration of on-chip batteries with microelectronics.

Molybdenum disulfide (MoS 2 ) is an earth-abundant and low-cost hydrogen evolving electrocatalyst with the potential to replace traditional noble metal catalysts. The catalytic activity can be significantly enhanced after modification due to higher conductivity and enriched active sites. However, the underlying mechanism of the influence of the resistance of electrode material and contact resistance on the hydrogen evolution reaction (HER) process is unclear. Herein, we present a systematic study to understand the relationship between HER performance and electrode conductivity, which is bi-tuned through the electric field and photoelectrical effect. It was found that the onset overpotential consistently decreased with the increase of electrode conductivity. In addition, the reduction of the contact resistance resulted in a quicker electrochemical reaction process than enhancing the conductivity of the MoS 2 nanosheet. An onset overpotential of 89 mV was achieved under 60 mW/cm 2 sunlight illumination (0.6 sun) and a simultaneous gate voltage of 3 V. These physical strategies can also be applied to other catalysts, and offer new directions to improve HER catalytic performance of semiconductor materials.