Producing indispensable hydrogen and oxygen for social development via water electrolysis shows more prospects than other technologies. Although electrocatalysts have been explored for centuries, a ...universal activity descriptor for both hydrogen‐evolution reaction (HER) and oxygen‐evolution reaction (OER) is not yet developed. Moreover, a unifying concept is not yet established to simultaneously understand HER/OER mechanisms. Here, the relationships between HER/OER activities in three common electrolytes and over ten representative material properties on 12 3d‐metal‐based model oxides are rationally bridged through statistical methodologies. The orbital charge‐transfer energy (Δ) can serve as an ideal universal descriptor, where a neither too large nor too small Δ (≈1 eV) with optimal electron‐cloud density around Fermi level affords the best activities, fulfilling Sabatier's principle. Systematic experiments and computations unravel that pristine oxide with Δ ≈ 1 eV possesses metal‐like high‐valence configurations and active lattice‐oxygen sites to help adsorb key protons in HER and induce lattice‐oxygen participation in the OER, respectively. After reactions, partially generated metals in the HER and high‐valence hydroxides in the OER dominate proton adsorption and couple with pristine lattice‐oxygen activation, respectively. These can be successfully rationalized by the unifying orbital charge‐transfer theory. This work provides the foundation of rational material design and mechanism understanding for many potential applications.
A universal activity descriptor (orbital charge‐transfer energy) is successfully extracted from various materials’ physicochemical properties for both hydrogen‐evolving and oxygen‐evolving reactions in multiple electrolytes. Systematic experiments and computations reveal the life‐cycle HER and OER mechanisms and identify the unifying orbital charge‐transfer theory as a powerful mechanism analysis tool and foundation.
This four-week, randomized, double-blind, placebo-controlled study investigated the effects of
PS128 (PS128) on boys with autism spectrum disorder (ASD) aged 7-15 in Taiwan. All subjects fulfilled ...the criteria for ASD diagnosis of DSM-V and the Autism Diagnostic Interview-Revised (ADI-R). Questionnaires used for the primary outcome measure include the Autism Behavior Checklist-Taiwan version (ABC-T), the Social Responsiveness Scale (SRS) and the Child Behavior Checklist (CBCL). The Swanson, Nolan, and Pelham-IV-Taiwan version (SNAP-IV) and the Clinical Global Impression-improvement (CGI-I) were used for the secondary outcome measure. The results showed that PS128 ameliorated opposition/defiance behaviors, and that the total score of SNAP-IV for younger children (aged 712) improved significantly compared with the placebo group. Additionally, several elements were also notably improved in the PS128 group after 28-day consumption of PS128. Further studies are needed to better clarify the effects of PS128 for younger children with ASD on broader symptoms.
Corner‐sharing and edge‐sharing networks are the two most important material genomes. Inspired by the efficient electron transport capacity of corner‐sharing structures and the low steric hindrance ...of edge‐sharing units, an attempt is made to exert both merits by combining these two networks. Here, a unique self‐assembled hybrid SrCo0.55Fe0.5O3‐δ nanorod composed of a corner‐sharing SrCo0.5Fe0.5O3‐δ phase and edge‐sharing Co3O4 structure is synthesized through a Co‐site enrichment method, which exhibits the low overpotentials of 310 and 290 mV at 10 mA cm–2 for oxygen‐evolving reaction in 0.1 m and 1.0 m KOH, respectively. This efficiency is attributed to the high Co valence with strong CoO covalence and the short distance between CoCo/Fe metal active sites in hybrid nanorods, realizing a synergistic benefit. Combined multiple operando/ex situ characterizations and computational studies show that the edge‐sharing units in hybrid nanorods can help facilitate the deprotonation step of lattice oxygen mechanism (LOM) while the corner‐sharing motifs can accelerate the electron transport during LOM processes, triggering an unusual lattice‐oxygen activation. This methodology of combining important material structural genomes can offer meaningful insights and guidance for various catalytic applications.
Based on material structural genomes, a unique hybrid‐phase SrCo0.55Fe0.5O3‐δ nanorod composed of corner‐sharing units (SrCo0.5Fe0.5O3‐δ perovskite) with strong electron transport capacity and edge‐sharing motifs (Co3O4 spinel) with low reaction steric hindrance by a self‐assembled Co‐site enrichment method are developed. SrCo0.55Fe0.5O3‐δ nanorod exhibits efficient oxygen‐evolving performance with exceptional lattice oxygen activation.
The rational fabrication of Pt‐free catalysts for driving the development of practical applications in alkaline water electrolysis and fuel cells is promising but challenging. Herein, a promising ...approach is outlined for the rational design of multimetallic catalysts comprising multiple active sites including Pd nanoclusters and Ru single atoms anchored at the defective sites of Ni(OH)2 to simultaneously enhance hydrogen evolution reactions (HER) and ethanol oxidation reactions (EOR). Remarkably, Pd12Ru3/Ni(OH)2/C exhibits a remarkably reduced HER overpotential (16.1 mV@10 mA cm−2 with a Tafel slope of 21.8 mV dec−1) as compared to commercial 20 wt.% Pt/C (26.0 mV@10 mA cm−2, 32.5 mV dec−1). More importantly, Pd12Ru3/Ni(OH)2/C possesses a self‐optimized overpotential to 12.5 mV@10 mA cm−2 after 20 000 cycles stability test while a significantly decreased performance for commercial 20wt.% Pt/C (64.5 mV@10 mA cm−2 after 5000 cycles). The mass activity of Pd12Ru3/Ni(OH)2/C for the EOR is up to 3.724 A mgPdRu−1, ≈20 times higher than that of commercial Pd/C. Electrochemical in situ Fourier transform infrared measurements confirm the enhanced CO2 selectivity of Pd12Ru3/Ni(OH)2/C while synergistic and electronic effects of adjacent Ru, Pd, and OHad adsorption on Ni(OH)2 at low potential play a key role during EOR.
The Pd12Ru3/Ni(OH)2/C catalyst with the novel nanostructure of Pd nanoclusters and Ru single atoms anchored at the defective sites of Ni(OH)2 is designed and prepared, enhancing its catalytic performance for hydrogen evolution reaction and ethanol electrocatalytic oxidation reactions due to the synergistic and electronic effect of Ni(OH)2, Ru single atoms and Pd clusters.
Identifying real active sites and understanding the mechanism of oxygen evolution reaction (OER) are still a big challenge today for developing efficient electrochemical catalysts in renewable energy ...technologies. Here, using a combined in situ/operando experiments and theory, the catalytic mechanism of the ordered OER active Co and Ir ions in Sr2CoIrO6−δ is studied, which exhibits an unprecedented low overpotential 210 mV to achieve 10 mA cm–2, ranking the highest performance among perovskite‐based solid‐state catalysts. Operando X‐ray absorption spectroscopies as a function of applied voltage indicates that Ir4+ ion is gradually converted into extremely high‐valence Ir5+/6+, while the part of Co3+ ion is transferred into Co4+ under OER process. Density functional theory calculations explicitly reveal the order Co‐O‐Ir network as an origin of ultrahigh OER activity. The work opens a promising path to overcome the sluggish kinetics of OER bottleneck for water splitting via proper arrangements of the multi‐active sites in catalyst.
Operando experimental observation of a gradual oxidation state transition from Ir4+ to Ir5+ and further to Ir6+ and theoretical simulation expatiates the origin of ultrafast electrocatalytic water oxidation of the Sr2CoIrO6−δ catalyst with Co‐O‐Ir ordered arrangement.
Shape control has realized huge success for developing efficient Pd/Pt‐based nanocatalysts, but the control of Ru‐based nanocrystals remains a formidable challenge due to the inherent anisotropy in ...hexagonal closed‐packed nanocrystals. Herein, a class of unique RuCo nanoscrews (NSs) for water electrosplitting is successfully synthesized with rough surfaces and the exposure of steps and edges. Those high‐index faceted RuCo NSs show superior performance for overall water electrosplitting, where a low cell voltage of 1.524 V (@ 10 mA cm−2) and excellent stability for more than 20 h (@ 10 mA cm−2) for overall water electrosplitting in 1 m KOH is achieved. The enhanced performance of RuCo NSs is due to the optimization of the binding energy with the intermediate species and the reduced energy barrier of water dissociation. Density functional theory calculations reveal that the RuCo NS structure intrinsically endows various ridges and edges, which create low coordinated Ru‐ and Co‐sites. These active Ru‐ and Co‐sites present high efficiencies in electronic exchange and transfer between adsorbing O species and nearby lattice sites, guaranteeing the high H2O‐splitting activities. This present work opens up a new strategy for creating high‐performance electrocatalysts for water splitting.
A RuCo electrocatalyst with abundant high index facets is successfully fabricated with superior performance for water‐splitting in an alkaline environment, which is attributed to the simultaneous facilitation of both an alloying effect and high‐index facets. This work supplies significant insights for future research to further overcome the challenge of realizing bimetallic electrocatalysts with high‐index facets.
X‐ray circular dichroism, arising from the contrast in X‐ray absorption between opposite photon helicities, serves as a spectroscopic tool to measure the magnetization of ferromagnetic materials and ...identify the handedness of chiral crystals. Antiferromagnets with crystallographic chirality typically lack X‐ray magnetic circular dichroism because of time‐reversal symmetry, yet exhibit weak X‐ray natural circular dichroism. Here, the observation of giant natural circular dichroism in the Ni L3‐edge X‐ray absorption of Ni3TeO6 is reported, a polar and chiral antiferromagnet with effective time‐reversal symmetry. To unravel this intriguing phenomenon, a phenomenological model is proposed that classifies the movement of photons in a chiral crystal within the same symmetry class as that of a magnetic field. The coupling of X‐ray polarization with the induced magnetization yields giant X‐ray natural circular dichroism, revealing typical ferromagnetic behaviors allowed by the symmetry in an antiferromagnet, i.e., the altermagnetism of Ni3TeO6. The findings provide evidence for the interplay between magnetism and crystal chirality in natural optical activity. Additionally, the first example of a new class of magnetic materials exhibiting circular dichroism is established with time‐reversal symmetry.
The article reveals a new type of altermagnet, in which the symmetry allows for typical ferromagnetic behaviors. It presents X‐ray circular dichroism observed in a chiral antiferromagnet with time‐reversal symmetry. This phenomenon contrasts conventional X‐ray magnetic circular dichroism. As X‐rays propagate through the material, the Berry curvature, arising from the inversion symmetry breaking, gives rise to distinct circular dichroism.
An 8-channel closed-loop neural-prosthetic SoC is presented for real-time intracranial EEG (iEEG) acquisition, seizure detection, and electrical stimulation in order to suppress epileptic seizures. ...The SoC is composed of eight energy-efficient analog front-end amplifiers (AFEAs), a 10-b delta-modulated SAR ADC (DMSAR ADC), a configurable bio-signal processor (BSP), and an adaptive high-voltage-tolerant stimulator. A wireless power-and-data transmission system is also embedded. By leveraging T-connected pseudo-resistors, the high-pass (low-pass) cutoff frequency of the AFEAs can be adjusted from 0.1 to 10 Hz (0.8 to 7 kHz). The noise-efficiency factor (NEF) of the AFEA is 1.77, and the DMSAR ADC achieves an ENOB of 9.57 bits. The BSP extracts the epileptic features from time-domain entropy and frequency spectrum for seizure detection. A constant 30- μA stimulus current is delivered by closed-loop control. The acquired signals are transmitted with on-off keying (OOK) modulation at 4 Mbps over the MedRadio band for monitoring. A multi-LDO topology is adopted to mitigate the interferences across different power domains. The proposed SoC is fabricated in 0.18- μm CMOS and occupies 13.47 mm 2 . Verified on Long Evans rats, the proposed SoC dissipates 2.8 mW and achieves high detection accuracy (> 92%) within 0.8 s.
Abstract
Designing efficient catalyst for the oxygen evolution reaction (OER) is of importance for energy conversion devices. The anionic redox allows formation of O-O bonds and offers higher OER ...activity than the conventional metal sites. Here, we successfully prepare LiNiO
2
with a dominant 3
d
8
L
configuration (
L
is a hole at O 2
p
) under high oxygen pressure, and achieve a double ligand holes 3
d
8
L
2
under OER since one electron removal occurs at O 2
p
orbitals for Ni
III
oxides. LiNiO
2
exhibits super-efficient OER activity among LiMO
2
,
R
MO
3
(M = transition metal,
R
= rare earth) and other unary 3d catalysts. Multiple in situ/operando spectroscopies reveal Ni
III
→Ni
IV
transition together with Li-removal during OER. Our theory indicates that Ni
IV
(3
d
8
L
2
) leads to direct O-O coupling between lattice oxygen and *O intermediates accelerating the OER activity. These findings highlight a new way to design the lattice oxygen redox with enough ligand holes created in OER process.
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