Effect of boron–nitrogen bonding on oxygen reduction reaction activity of BN Co-doped activated porous carbons

Abstract

In this work, we have synthesized N and S co-doped mesoporous carbons as highly efficient electrocatalysts to investigate the influence of annealing temperatures on electrocatalytic activity of N and S co-doped mesoporous carbon for oxygen reduction reaction (ORR) in alkaline media. The catalysts were prepared through silica hard template method, thermal annealing of ferrous chloride (FeCl 2 4H 2 O) and polyquaternium-46 (PQ) in nitrogen. Results of electrochemical characterizations for ORR were studied by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) employing rotating disk electrode (RDE) technique. The peroxide yield (H 2 O 2 %) and electron transfer number (n) on the mesoporous carbon catalyzed electrode were investigated via the rotating ring-disk electrode (RRDE) experiments to study the ORR catalytic pathway of the catalysts. It is found that the temperature of the heat treatment is a significant parameter in synthesizing the high performance ORR catalysts. Of the three catalysts, FeCl 2-PQ-800 o C showed superior catalytic activity with onset potential at 0.965 V and half-wave potential at 0.807 V. The corresponding electron transfer number was greater than 3.81, indicating that the ORR process proceeds mainly via a four-electron mechanism.

Highly Rechargeable Lithium‐CO2 Batteries with a Boron‐ and Nitrogen‐Codoped Holey‐Graphene Cathode

“…No peak attributable to N−B bond (typically centered at around 397.7 eV) was observed, indicating no B−N bond formation during the B,N‐codoping process. The absence of B−N bonding in BN‐hG could also be confirmed by the high‐resolution B1s spectrum (Figure g), which shows only one peak at around 189.2 eV attributable to the B−C bond …”

Boron‐Doped Polygonal Carbon Nano‐Onions: Synthesis and Applications in Electrochemical Energy Storage

“…The IR band centered at 1220 results from the planar B−C units . The signals at approximately 1370 cm − 1 can be attributed to B−N or N−C stretching, C−C ring stretching, or asymmetric B−O stretching …”

“…[56] Thesignals at approximately 1370 cm À1 can be attributedt oB ÀN [57] or NÀCs tretching, CÀCr ing stretching, or asymmetricB ÀOs tretching. [58] It was of interestt oe stimate thermal stabilityo ft he undoped CNOs and B-CNOs in air,A r, and O 2 atmospheres by derivatography.T he temperature necessary for the removal of the amorphousc arbon formed during the annealing of NDsi na ir is lower than the decompositiont emperature of the pristine CNs. The onset of oxidation, inflection,a nd endt emperatures are listed in Table SI2 in the Supporting Information, representing the initial weight loss, the maximum weight loss, and the final weighti nt he differential-thermogravimetric analysis (TGA-DTG) graphs, respectively.T he lowest inflection temperature was observed fort he pristine CNOs, I t = 650 8C( Ta bleSI2 in the Supporting Information andF igure 7a,c urve 1), with at otal weight loss of 98 %a t7 00 8C.…”

Highly Rechargeable Lithium‐CO2 Batteries with a Boron‐ and Nitrogen‐Codoped Holey‐Graphene Cathode

“…[14c] No peak attributable to N À Bbond (typically centered at around 397.7 eV) was observed, [21] indicating no BÀNb ond formation during the B,N-codoping process.T he absence of BÀNb onding in BN-hG could also be confirmed by the high-resolution B1s spectrum (Figure 1g), which shows only one peak at around 189.2 eV attributable to the B À C bond. [22] To investigate the effect of B,Ncodoping on the catalytic activity for CO 2 reduction and evolution reactions,L i-CO 2 cells were assembled with hG or BN-hG cathodes and discharged/charged at ac urrent density of 0.3 Ag À1 between 2.0 and 4.5 V. Figure 2a reproduces the initial discharge/ charge curves,w hich show that the discharge voltage of the cell with an hG cathode decreased quickly with time,and that ad ischarge capacity of 6620 mAh g À1 was obtained when being discharged to 2.0 V. In contrast, al ong and flat discharge plateau was observed at ad ischarge voltage of 2.75 Vand current density of 0.3 Ag À1 for the cell with aBN-hG cathode,i ndicating that the CO 2 reduction kinetics was significantly enhanced by B,N-codoping. Theinitial discharge capacity of the cell with aBN-hG cathode reached as high as 16 033 mAh g À1 ,w hich is about 2.4 times that of the cell with an hG cathode.More importantly,the value of 16 033 mAh g À1 is comparable to,ifnot higher than, that of most reported Li-O 2 batteries, [2b] indicating ag reat potential for Li-CO 2 batteries based on aB N-hG cathode.F urthermore,areversible charge capacity of 14 996 mAh g À1 was obtained upon recharging the Li-CO 2 cell with aB N-hG cathode back to 4.5 V, yielding an initial Coulombic efficiency of 93.5 %.…”