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In this work, we report a facile method to prepare P, N co‐doped porous carbon (PNPC) by the carbonization of covalent organic polymer (COP) used as efficient metal‐free electrocatalyst for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Overpotential is only 150 mV for the PNPC electrocatalyst to reach 10 mA cm−2 in the acidic medium due to the heteroatom dopants in the carbon matrix; meanwhile, stable HER activity is recorded during 5000 potential cycles. Additionally, overpotential is 343 mV for PNPC electrocatalyst to drive OER catalysis with 10 mA cm−2, which is comparable to the benchmarked IrO2 (320 mV). Similarly, PNPC electrocatalyst can achieve a Pt‐like ORR catalytic activity. The power density of the assembled rechargeable zinc‐air battery (ZAB) is 1.8 times higher than that of the commercial system (Pt/C−IrO2) and charge‐discharge voltage gap is well maintained during 20 h test, implying the high stability of the formed PNPC electrocatalyst. [ABSTRACT FROM AUTHOR]

W/W2C heterostructured nanoparticles encapsulated by N,P dual-doped carbon (W/W2C@NPC) fabricated by the carbonization of in situ polymerized polyaniline (PANI) and phosphotungstic acid require low overpotentials of 55 mV and 82 mV vs. RHE to achieve a cathodic current density of 10 mA cm−2 in acidic and alkaline electrolytes, respectively. [ABSTRACT FROM AUTHOR]

As well known, heteroatom doped carbon material served as metal‐free electrocatalyst for hydrogen evolution (HER) and oxygen reduction reactions (ORR) particularly relies on the heteroatom doping level. Here, we report a 3D porous nitrogen doped carbon (PNC) electrocatalyst with superior HER and ORR electrocatalytic activities derived from the calcination of the discarded cigarette butt and dicyandiamide possessing a high nitrogen content (20 at%). PNC electrocatalyst only demands 143 mV versus RHE to achieve 10 mA cm−2 ascribed to the high nitrogen percentile in PNC electrocatalyst favorable for constructing successive active centers contributing to efficiently catalyzing HER. Ignorable degradation in HER activity observed after 10000 potential cycles as well as undetectable decay in HER performance recorded after 12 h operation indicate high stability of PNC electrocatalyst. Meanwhile, half‐wave potential of PNC electrocatalyst reaches 0.81 V versus RHE in 1 M KOH electrolyte. Additionally, stable ORR activity attained after 1000 potential cycles is indicative of high stability. A comparably high zinc‐air battery performance with maximum power density of 66 mW cm−2 is achieved by PNC electrocatalyst. This study highlights the importance of nitrogen doping level in metal‐free electrocatalyst for boosting HER and ORR activities. What? No metal! A 3D porous nitrogen doped carbon (PNC) electrocatalyst with superior HER and ORR electrocatalytic activities derived from the calcination of the discarded cigarette butt and dicyandiamide possessing a high nitrogen content (20 at%). [ABSTRACT FROM AUTHOR]

• Atomic layer Co 3 O 4-x nanosheets (1 nm) are synthesized. • Robust OER and ORR activities are achieved for atomic layer Co 3 O 4-x nanosheets. • Rechargeable ZAB performance of Co 3 O 4-x nanosheets is 1.7 fold than Pt/C-IrO 2. Stable and efficient bifunctional electrocatalyst for air electrode is still of challenge for rechargeable zinc-air batteries (ZABs). Here, we report an atomic layer oxygen defect cobalt oxides (Co 3 O 4-x) nanosheets (1 nm) as efficient electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Due to the atomic layer nanosheets, more oxygen defects are formed during plasma treatment enabling effective OER catalysis with overpotential of only 309 mV, which is lower compared to benchmarking IrO 2 (313 mV). Meanwhile, a Pt-like ORR activity is achieved for Co 3 O 4-x due to the atomic layer nanosheets with highly exposed active sites and loosened binding strength between Co3+ and O 2 /OH−. The battery performance of Co 3 O 4-x nanosheets is 1.7 times higher than that of Pt/C-IrO 2 based ZABs. Besides, Co 3 O 4-x nanosheets exhibit undetectable degradation in battery performance after galvanostatic discharge-charge with 5 mA cm−2 for 150 h implying the superior stability of the atomic layer Co 3 O 4-x nanosheets. All-solid-sate ZABs fabricated from Co 3 O 4-x nanosheets perform an impressive power density of 57 mW cm−2 and stable galvanostatic discharge-charge voltage for 2 h demonstrating that Co 3 O 4-x nanosheets can be utilized as air electrode for practical application. [ABSTRACT FROM AUTHOR]

Cu-Ru dual atoms anchored to N-doped phosphorene shows the synergy effect to achieve nitrogen reduction efficiently [Display omitted] • Cu-Ru dual atoms show the synergy effect and promote the eNRR property of Cu based catalyst. • Cu-Ru/N 4 -BP shows excellent eNRR property than HER property. • The lower NH 3 desorption energy makes catalytic sites be exposed again, benefiting for higher catalytic activity. • N 2 molecules can be reduced into NH 3 on the Cu-Ru/N 4 -BP with the ultra-lower overpotential of 0.30 V. The Harber-Bosch method was considered as a milestone in the field of industrial production because this method can utilize N 2 to produce NH 3. However, this process severely consumes energy resources and produces a mass of undesirable byproducts and pollution, which unsatisfied the international consensus of "carbon neutrality". Exploring an efficient electrocatalyst for achieving N 2 reduction is becoming extreme imperative for the novel catalytic design. Here, we constructed 17 kinds of Cu based transition metal dual atoms anchored to N-doped phosphorene electrocatalyst (Cu-TM/N 4 -BP) as the potential candidates for the N 2 fixation based on the first-principles calculations. The Ru atom promotes the N 2 adsorption property of Cu atom, stretches N≡N triple bond, and thus activates N 2 molecules. The Cu-Ru dual atoms anchored to N-doped phosphorene (Cu-Ru/N 4 -BP) shows excellent N 2 reduction property than hydrogen evolution reaction. The N 2 molecules can be efficiently reduced into NH 3 on the Cu-Ru/N 4 -BP with the ultra-lower overpotential of 0.30 V and NH 3 desorption energy. This study provides a novel way at the atomic level to explore phosphorene based electrocatalyst with lower overpotential and long durability for N 2 reduction in the experiments. [ABSTRACT FROM AUTHOR]