Novel Two-Dimensional Carbon–Chromium Nitride-Based Composite as an Electrocatalyst for Oxygen Reduction Reaction

Abstract

For future pollution-free renewable energy production, platinum group metal (PGM)-free electrocatalysts are highly required for oxygen reduction reaction (ORR) to avoid all possible Fenton reactions and to make fuel cell more economical. Therefore, in this study, to overcome traditional electrocatalyst limitations, we applied facile method to synthesize robust mesoporous CrN-reduced graphene oxide (rGO) nanocomposite with MnO (thereafter, Cr/rGO composite with MnO) as an electrocatalyst by efficient one-step sol-gel method by ammonolysis at 900°C for 9 h. Synthesized porous structures of Cr/rGO nanocomposite with MnO have the highest estimated surface area of 379 m2·g−1, higher than that of the carbon black (216 m2·gcat-1) support, and almost uniform pore size distribution of about 4 nm. The Cr/rGO nanocomposites with MnO exhibit enhanced electrocatalytic ORR properties with estimated high half-wave potential of 0.89 V vs. the reversible hydrogen electrode (RHE) and current density of 5.90 mA·cm−2, compared with that of benchmark 20% Pt/C electrode (0.84 V, 5.50 mA·cm−2), with noticeable methanol tolerance and significantly enhanced stability in alkaline media. Hence, the Cr/rGO nanocomposites with MnO showed superior performance to 20 wt.% Pt/C; their half-wave potentials were 50 mV high, and the limiting current density was 0.40 mA·cm−2 high. In alkaline anion exchange membrane fuel cell (AAEMFC) setup, this cell delivers a power density of 309 mW·cm−2 for Cr/rGO nanocomposite with MnO, demonstrating its potential use for energy conversion applications. The nanosized Cr/rGO metallic crystalline nanocomposites with MnO gave a large active surface area owing to the presence of rGO, which also has an effect on the charge distribution and electronic states. Hence, it may be the reason that Cr/rGO nanocomposites with MnO, acting as more active and more stable catalytic materials, boosted the electrocatalytic properties. The synergistic consequence in nanosized Cr/rGO composite with MnO imparts the materials' high electron mobility and thus robust ORR activity in 0.1 M of KOH solution. This potential method is highly efficient for synthesis of large-scale, non-noble-metal-based electrocatalytic (NNME) materials (i.e., Cr/rGO nanocomposite with MnO) on the gram level and is efficient in preparing novel, low-cost, and more stable non-PGM catalysts for fuel cells.

Recent developments in emerging two-dimensional materials and their applications

“…[24][25][26] The emergence of novel 2D materials other than graphene has illustrated their extraordinary potential applications for diverse technologies, in addition to concentrating on new discoveries in elementary science, such as sensors, LEDs, FETs, physics, catalysis, biomedicine, and environmental science. [27][28][29] The undeniable requirements of superior performance and lower power use in electronic systems are the major motivators of the electronics industry's search for device architectures based on novel 2D materials.…”

Recent Progress, Challenges, and Prospects in Two-Dimensional Photo-Catalyst Materials and Environmental Remediation

“…In the past, larger part of worldwide energy formation was based on fossil fuel, which increases environment pollution and hence causes global warming [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In this modern society, development in different industries causes rapid population growth, which is further estimated to increase by two factors: the current energy required by 2050 to run industries around globe and their household uses [2][3][4][15][16][17][18][19][20][21][22][23][24][25][26]. Presently, world's energy supplies are mainly reliant on fossil fuels, for example, coal, petroleum, and natural gases, which are quickly being spent.…”

“…The technical challenges to increase an industrially talented chemical process to protect a clean, renewable energy and to reduce harmful ecological impact are connected with the use of fossil fuels [ 2 , 3 , 19 , 22 ]. In this regard, renewable sustainable energy production is one of the significant solutions, especially hydrogen (H 2 )-based energy creation by photo-catalysts as well as electrocatalysts [ 2 – 4 , 18 , 19 , 21 , 25 ]. Here, we will mainly concern on photo-catalysts.…”

“…The H 2 has the maximum energy contented per weight in combustion fuels and manufactures simply water (H 2 O) as by-product [ 3 , 4 , 19 ]. Thus far, straightforward transfer of solar energy to fuel energy (H 2 ) and chemical energy was viewed as one of the green renewable ways to deal with energy and environmental pollution issues in the future [ 2 – 4 , 17 , 18 , 21 , 23 – 25 ]. Hence, H 2 is considered as an ultra-clean, powerful, environment friendly, and hopeful another choice for meeting the future fuel necessities with environmental safety by less release of greenhouse gasses [ 2 – 4 , 17 – 19 , 21 , 23 , 24 ].…”

Sensing Applications of Atomically Thin Group IV Carbon Siblings Xenes: Progress, Challenges, and Prospects

“…The most obvious alternatives for G are other elements within same group IVA, since other elements within same group have same number of e − s. The discovery of this novel area of 2DMs has just started, its assured not fully achieved and degree of its possible properties and their highly efficient commercial level device applications still remain somehow basically unexploited. [8][9][10][55][56][57][58][59][60][61][62][63][64] The numerous theoretical calculations evaluating their basic properties, while experimental investigations are just in their early stage, as realistic formation ways are being investigated to launch a definite synthesis methods and limitations. The other neighbor group (VA, VIA) removed this barrier with a sizeable BG, which is highly demandable in the logic electronics.…”