Iron Phosphide Incorporated into Iron‐Treated Heteroatoms‐Doped Porous Bio‐Carbon as Efficient Electrocatalyst for the Oxygen Reduction Reaction

Abstract

The development of electrocatalysts from inexpensive, natural sources has been an attractive subject owing to economic, environmental, sustainable, and social merits. Herein, Fe-treated heteroatoms (N, P, and S)-doped porous carbons are synthesized for the first time by pyrolysis of bio-char derived from abundant human urine waste as a single precursor for carbon and heteroatoms, using iron(III) acetylacetonate as an external Fe precursor, followed by acid leaching and activation with a second pyrolysis step in NH 3 . In particular, the sample prepared at a pyrolysis temperature of 800 8C (FeP-NSC-800) contains iron phosphide (FeP, Fe 2 P) in the high-porosity heteroatoms-doped carbon framework along with Fe traces, and exhibits excellent oxygen reduction reaction (ORR) activity and stability in both alkaline and acidic electrolytes as demonstrated in half-and single-cell tests. Such excellent ORR catalytic performance is ascribed to a synergistic effect of not only multiple active FeÀP, FeÀN, and pyridinic and graphitic N species in the electrocatalyst but also facile transport channels provided by its hierarchical porous structure with micro-/mesopores. In addition, the sample exhibits high long-term durability and methanol crossover resistance.

Pyrolytic Carbon‐coated Cu‐Fe Alloy Nanoparticles with High Catalytic Performance for Oxygen Electroreduction

“…Despite numerous attempts to exploit low‐cost and efficient non‐precious metal electrocatalysts to substitute traditional platinum‐based catalysts for oxygen reduction reaction (ORR) in the last several decades, it is still a long way for the large‐scale commercialization of these electrocatalysts in clean energy devices such as fuel cells and metal‐air batteries . In order to fulfil the requirements of the large‐scale commercial application, it is very crucial to seek the novel low‐cost non‐noble metal electrocatalysts with the higher ORR catalytic activity and durability.…”

“…[1][2][3][4][5] In order to fulfil the requirements of the large-scale commercial application,i ti sv ery crucial to seek the novel low-cost nonnoble metal electrocatalysts with the higher ORR catalytic activity and durability.C opper,w ith abundantr eserves and low costs, only one electron away from platinum in amount of the de lectrons in the secondary outer shell of the atom, has attracted much attention. [1][2][3][4][5] In order to fulfil the requirements of the large-scale commercial application,i ti sv ery crucial to seek the novel low-cost nonnoble metal electrocatalysts with the higher ORR catalytic activity and durability.C opper,w ith abundantr eserves and low costs, only one electron away from platinum in amount of the de lectrons in the secondary outer shell of the atom, has attracted much attention.…”

“…Despite numerous attempts to exploit low-cost and efficient non-precious metal electrocatalysts to substitute traditional platinum-based catalysts for oxygen reduction reaction (ORR) in the last severald ecades, it is stillal ong way for the largescale commercialization of these electrocatalysts in clean energy devicess uch as fuel cells and metal-air batteries. [1][2][3][4][5] In order to fulfil the requirements of the large-scale commercial application,i ti sv ery crucial to seek the novel low-cost nonnoble metal electrocatalysts with the higher ORR catalytic activity and durability.C opper,w ith abundantr eserves and low costs, only one electron away from platinum in amount of the de lectrons in the secondary outer shell of the atom, has attracted much attention. The half-wavep otential for ORR over the Cu particles encapsulated in N-doped carbon shells reached0 .83 V RHE (relative to the reversible hydrogen electrode) and was 20 mV lower than that over the commercial Pt/ Cc atalyst.…”

Phosphorus‐Based Electrocatalysts: Black Phosphorus, Metal Phosphides, and Phosphates

“…Heteroatom doping (e.g., N) in a carbon structure could induce charge redistribution to make adjacent carbon atoms as the active sites for the ORR. [ 188 ] In the phosphide@carbon hybrid‐type catalysts, although the encased phosphides didn't contact with the oxygen intermediates directly during the ORR process, they still could activate the surrounding graphitic carbon layer synergistically, endowing the carbon layer with high activity toward the ORR. For instance, Lin and co‐workers reported a CoP/defective carbon (DC) hybrid (Figure 7d,e), where the interfacial polarized electrons accumulated at the surface of DC contributed to the enhanced ORR activity, and the holes accumulated at CoP nanoparticles were helpful to the OER process, as demonstrated by their electrochemical tests (Figure 7f–h).…”

Hydrothermal Carbon/Carbon Nanotube Composites as Electrocatalysts for the Oxygen Reduction Reaction

“…Nevertheless, the chemical properties of HTCs need to be modified in order to approach the outstanding electrochemical performance of Pt-electrocatalyst reference materials [23,24]. These modifications can be achieved by the incorporation of heteroatoms like nitrogen, sulfur, phosphorus, or boron and/or advanced carbon materials like graphene oxide or carbon nanotubes (CNTs) [9,12,13,17,[25][26][27][28]. Nitrogen is the most promising heteroatom for ORR, as pyridinic nitrogen favors the bonding of oxygen to the adjacent carbon, while the presence of quaternary nitrogen favors oxygen dissociation [7,29].…”