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has received considerable attention as a promising energy storage media owing to its high gravimetric energy density (142 MJ kg −1 ) and near-zero carbon emission power generation. [7][8][9][10][11][12] Currently, both alkaline and protonconducting polymer electrolyte membrane water electrolysis (PEMWE), also known as proton exchange membrane water electrolysis, are well established as commercial or near-commercial electrochemical water-splitting technologies. [13,14] Compared to alkaline water electrolysis, PEMWE has the advantages of faster dynamics owing to high ionic conductivity, operation at higher current density (maximum 2-3 A cm −2 ), and high-purity H 2 production. [15,16] However, PEMWE necessitates the use of noble-metal-based electrocatalysts on both cathode and anode. Various kinds of electrocatalysts have been developed to replace platinum/ carbon (Pt/C) for the hydrogen evolution reaction (HER) at the cathode. [17][18][19][20][21] However, currently available electrocatalysts for the oxygen evolution reaction (OER) at the anode still depend on iridium (Ir), ruthenium (Ru), or their oxide forms. The high cost and scarcity of Ir and Ru limit the large-scale application of PEMWE. [22,23] Although some noblemetal-free materials show OER activity in strongly acidic solutions, many of them are still unstable in acidic solutions and exhibit inferior electrocatalytic OER activity than noble-metalbased materials. [24,25] Furthermore, especially in acidic media, oxygen evolution is even more limited in the water-splitting process owing to the slow kinetics of water oxidation originating from the complex four-proton-coupled electron transfer reactions as well as additional water dissociation processes. [26][27][28] As such, it is mandatory to develop noble-metal-reduced OER electrocatalysts with a high electrocatalytic activity that are well tolerated in acidic solutions. Some OER electrocatalysts which could be tolerated in acidic solutions were reported before 2010. However, since 2015, intensive research has been carried out to address the other aforementioned issues by developing alternative electrocatalytic materials for the OER in acidic solutions.Recently, Ir-or Ru-based perovskite oxides have emerged as promising novel OER electrocatalysts in acidic solutions, owing to their multimetal-oxide nature that can reduce the usage of noble metal. Perovskite oxides have various structures, i.e., single perovskite structure with the general formula ABO 3 , double perovskite structure with the formula A 2 BB′O 6 (double Proton-conducting polymer electrolyte membrane water electrolysis (PEMWE) is a promising technology for generating clean and sustainable hydrogen fuels from water. However, PEMWE requires the use of expensive electrocatalysts; the currently available electrocatalysts for the oxygen evolution reaction (OER) depend on noble metals (Ir, Ru). Since noble metals are expensive, commercialization of PEMWE remains elusive. In addition, PEMWE suffers from the very slow kinetics of the OER in acidic medi...

For mass production of hydrogen fuel by electrochemical water splitting, seawater electrolysis is preferred over freshwater electrolysis because of the abundance of seawater in nature. However, the electrochemically active anions in seawater can cause the corrosion of electrodes or undesirable side reactions during the anodic reaction at the anode, thus degrading the overall system efficiency. Hence, it is imperative to develop highly active and stable oxygen evolution reaction (OER) electrocatalysts for efficient seawater electrolysis. In this study, carbon-coated sodium cobalt−iron pyrophosphate (Na 2 Co 1−x Fe x P 2 O 7 /C, 0 ≤ x ≤ 1) nanoparticles (NCFPO/C NPs) and NCFPO/C NPs loaded on a carbon cloth (NCFPO/C@CC) are fabricated as a promising OER electrocatalyst for alkaline seawater electrolysis. The electrocatalytic OER performance of the NCFPO/C NPs is optimized by controlling their Co/Fe ratio. NCFPO/C@CC acts as an efficient OER electrocatalyst during the OER test in an alkaline saline solution without corroding the electrode and generating reactive chloride species. It also exhibits long-term stability and durability with continuous oxygen generation. In addition, NCFPO/C@CC shows the electrocatalytic OER activity in alkaline seawater, demonstrating that NCFPO/C is a promising candidate as an OER electrocatalyst for realistic alkaline seawater electrolysis.

Developing low-cost, highly active, and stable bifunctional electrocatalysts is a challenging issue in electrochemical water electrolysis. Building on 3D architectured electrocatalysts through structural and compositional engineering is an effective strategy to enhance catalytic activities as well as stability and durability. Herein, 3D architectures of quaternary Co-Ni-S-P compounds coupled with graphene ((Co 1−x Ni x )(S 1−y P y ) 2 /G) electrocatalysts are proposed, in which nanosheets are self-assembled to form 3D architectures with round and flat doughnut-like shapes, toward overall water splitting. Benefiting from the 3D architectures and Ni, P substitution, (Co 1−x Ni x )(S 1−y P y ) 2 /G exhibits superior electrocatalytic activities with low overpotentials of 117 and 285 mV at 10 mA cm −2 and Tafel slopes of 85 and 105 mV dec −1 for hydrogen and oxygen evolution reactions, respectively, in alkaline media. In addition, minimal increases in overpotential are observed, even after the 10 000th voltammetric cycle and continuous chronopotentiometric testing over 50-100 h, confirming the high stability and durability of (Co 1−x Ni x )(S 1−y P y ) 2 /G. When used as both cathode and anode, (Co 1−x Ni x )(S 1−y P y ) 2 /G achieves excellent overall water splitting performance with a cell potential as low as 1.65 V, reaching a current density of 10 mA cm −2 with no obvious decay after 50 h, demonstrating that (Co 1−x Ni x )(S 1−y P y ) 2 /G is an efficient bifunctional electrocatalyst for overall water splitting.

The objective of this study was to investigate changes in the natural language environments of families with typically-developing infants receiving language feedback in South Korea. Volunteer parents of 99 children aged 4–16 months were randomly divided into experimental and control groups. During 6 months’ intervention, the experimental group recorded weekly day-long automatically-analyzed LENA measures of language environment and viewed feedback, while the control group recorded only baseline, mid-period and post-test without feedback. LENA Adult Word Counts (AWC) and Conversational Turn (CT) counts correlated reasonably well with human transcripts. At baseline groups were not significantly different. At post-test there was no significant overall difference between experimental and control groups, but AWC and CT differences were significant for families below the 50th percentile at baseline. Korean parents whose linguistic environment was below average adapted their communicative interaction in response to linguistic feedback. The intervention has promise for use with at-risk families in many countries.