CuO Nanosheets Prepared by Dielectric Barrier Discharge Microplasma as Catalysts for the Oxygen Evolution Reaction

A method for constructing transition metal catalysts for the oxygen evolution reaction (OER) is proposed. Facile preparation is realized in the case of no added metal source via dielectric barrier discharge (DBD) microplasma under 10 min, and the thickness of the nanosheet is only 6.5 nm. The prepared ultrathin CuO nanosheets on copper foam (CuO UTNS/CF) display a catalytic activity of 262 mV overpotential (η) at 10 mA cm–2 for the OER in alkaline media. The as-prepared electrocatalyst guarantees appealing long-term durability (>90 h) and a high turnover frequency (TOF) of 0.488 mol O2 s–1 at 426 mV. Compared to CuO/CF prepared traditionally, the overpotential of CuO UTNS/CF can be directly reduced to 38 mV. Moreover, hydroxyl radicals (•OH) were identified as the intermediate products and a possible synthesis mechanism was preliminarily put forward. As a facile technology for the OER catalyst, we believe that DBD microplasma will provide a broad perspective for researchers

Diagrammatic illustration of the experimental design sequence.

Chinese education consists of two semesters each year. Semester 1 includes September to the following February. Semester 2 March to July. Thus the COVID-19 cohort undertook the second semester of their medical course during pandemic lockdown between March and July 2020.</p

Fig 2 -

The comparison between the students’ demographics for the pre-COVID-19 cohort (white bars) and COVID-19 cohort (grey bars) (A), students’ numbers stratified by sex (B), the average age of the students (C) and the students’ age stratified by sex (D).</p

Fig 3 -

Student academic performance by subject, English (A), Computer Science (B), Chinese History (C), Sports (D), Biochemistry (E), Anatomy (F), Histology (G) and Histology Practice (H). The white, light grey, middle grey and dark grey bars represent the men student in 2019, women student in 2019, men students in 2020 and women students in 2020, respectively. The Y-axis represents the mark in percentage points.</p

S1 Fig -

Validation of the pre-pandemic academic performance between the pre-COVID-19 cohort and COVID-19 cohort for the semester 1 studies undertaken prior to the pandemic on the subjects: Cell Biology, Advanced Mathematics, Chemistry and Medical Physics (A). The Y-axis represents the mark in percentage points. Validation of the marks achieved following stratification by sex for the two cohorts (B). (DOCX)</p

The academic performance achieved during progressive assessment in histology practice.

Daily performance mark (A), mid-term examination mark (B), final examination mark (C) and overall mark (D) are shown. The white, light grey, middle grey and dark grey bars represent the men student in 2019, women student in 2019, men students in 2020 and women students in 2020, respectively. The Y-axis represents the mark in percentage points.</p

S1 Data -

To control COVID-19 pandemic, complete lockdown was initiated in 2020. We investigated the impact of lockdown on tertiary-level academic performance, by comparing educational outcomes amongst first-year students during second semester of their medical course prior to and during lockdown. Evidence: The demographics, including educational outcomes of the two groups were not significantly different during semester one (prior to the lockdown). The academic performance amongst women was better than men prior to lockdown. However, the scores were improved significantly for both sexes during lockdown in 2020, following the complete online teaching, compared to that in 2019, showing no significant difference between men and women in 2020, for English and Chinese History. There were significant different scores between men and women in lab-based Histology Practice in 2019 (in-person tuition) and 2020 (online digital tuition), although only a significant improvement in women was observed between 2019 and 2020. Implication: the forced change to online delivery of the second semester of the first-year medical program in 2020 due to the COVID-19 pandemic did not result in any decline in assessment outcomes in any of the subjects undertaken. We believe extensive online digital media should continue to be available to students in future.</div