2-AT = 2-Aminothiazole	Hip = 1H-imidazo[4,5-f][1,10]phenanthroline	PANI = Polyaniline
2-mIm = 2-Methylimidazole	HMT = Hexamethylenetetramine	PBS = Phosphate buffer solution
4-py-TTF-4-py = 4-Pyridyl-tetrathiafulvalene-4-pyridyl	HNCSs = Hollow N-doped carbon microspheres	PEMFCs = Proton-exchange membrane fuel cells
AC = Activated carbon	HR-TEM = High-resolution TEM	PGM = Pt-group metal
BET = Brunauer–Emmet–-Teller	ICP = Inductively coupled plasma	PTA = Terephthalic acid
BIM = Benzimidazole	IPN = Interpenetrating polymer network	PVP = Polyvinylpyrrolidone
[bmim][Tf2N] = 1-Butyl-3-methylimidazoliumbis(trifiuoromethylsulfonyl) imide	IRES = Intermittent renewable energy sources	RDE = Rotating disk electrode
CNT = Carbon nanotube	IRMOF = Isoreticular metal organic framework	RHE = Reversible hydrogen electrode
CV = Cyclic voltammetry	JL = Diffusion-limited current density	rpm = Rotation per minute
CVD = Chemical vapor deposition	K-L = Koutecky–Levich	RRDE = Rotating ring-disk electrode
DAP = 2,6-diaminopyridine	LSV = Linear sweep voltammetry	SAED = Selected area electron diffraction
DFT = Density functional theory	MAC = Metal–ammonia complex	SCE = Saturated calomel electrode
DOE = Department of Energy	MEA = Membrane electrode assembly	SEM = Scanning electron microscopy
E1/2 = Half-wave potential	MIL = Materials of Institut Lavoisier (MOF class)	STEM = Scanning transmission electron microscopy
EDS/EDX = Energy-dispersive spectroscopy	MOF = Metal–organic frameworks	TCPP = Tetrakis(4-carboxyphenyl)porphyrin
Eonset = Onset potential	MOG = Metal–organic gel	TEM = Transmission electron microscopy
EXAFS = Fourier transform extended X-ray absorption fine structure	MWCNTs = Multi-walled carbon nanotubes	TEOS = Tetraethylorthosilicate
FeAc = Ferrous acetate	n = Electron transfer number	UIO = University of Oslo (MOF class)
Fe(acac)3 = Iron(III) 2,4-pentanedionate	n/a = Not applicable	XC-72R = Type of carbon black
FePc = Iron(II) phthalocyanine	NTCDA = 1,4,5,8-Naphthalenetetracarboxylic anhydride	XPS = X-ray photoelectron spectroscopy
GO = Graphene oxide	OER = Oxygen evolution reaction	XRD = X-ray diffraction
H3BTC = 1,3,5-Benzenetricarboxylic acid	ORR = Oxygen reduction reaction	ZIF = Zeolitic imidazolate framework
HAADF-STEM = High-angle annular dark-field STEM	P123 = Triblock copolymers poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)