136
Y. Li et al.
them achieved a kinetic current density of 99 A cm
−3 at 0.8 V by volume, and the
best data previously reported was 2.7 A cm
−3 , which is very close to the 2010 target
(130 A cm
−3 ) set by DOE.
Another breakthrough work was obtained by Wu et al. [217] in 2011. They
mixed carbon powder with large specific surface area, PANI-FeCo-C, transition metal
precursor (cobalt nitrate or ferric chloride), and short-chain aniline oligomer, and then
added (NH 4 ) 2 S 2 O 8 as an oxidant to completely polymerize the aniline. After polymerization, heat treatment was performed in a nitrogen atmosphere, and the obtained
sample was treated in a 0.5 M H 2 SO 4 solution at about 80 °C to remove unstable
metals. Full-cell performance tests show that the ORR performance of PANI-FeCoC as a non-noble metal catalyst is comparable to Pt/C. The H 2 /O 2 battery using
PANI-FeCo-C as the cathode catalyst runs at 0.4 V for 700 h, and there is almost no
degradation in performance. At different voltages, when PANI-FeCo-C is characterized by a rotating disk electrode method, its ORR performance does not substantially
decrease after 9,000 cycles, and in full-cell characterization, its current density after
30,000 cycles also rarely decrease.
In general, these compounds with catalytic activity must meet the following four
conditions: (1) contains a transition metal, mainly Fe, Co, Ni; (2) the source of N
can be a metal precursor compounds, N groups on the surface of the modified carbon
support, or nitrogen-containing gas in the reactor; (3) the source of carbon is the
macrocyclic compound and the support carbon; (4) generally at a high temperature
of 800 °C or higher. Although the treatment temperature is low and the catalyst has
high catalytic activity, it cannot maintain stability.
4.4.3.2 Me-P–C (M = Fe, Co, Ni) Based Catalyst
P and N are elements of the V A group, which have the same outer electrons and
similar chemical properties. Compared with N, P has a larger atomic radius and lower
electronegativity. Density functional theory (DFT) calculations show that when P is
doped into single-walled carbon nanotubes (SWCNTs), P can change the electron
transport properties of SWCNTs and show stronger adsorption capacity for acceptor
molecules(O 2 , etc.) [217, 218]. However, compared with the extensive research of
Me-N–C system, the research of Me-P–C-based catalysts is still in its infancy.
Wu et al. [219] first prepared carbon powder by hydrothermally hydrothermal
method using sucrose as a raw material, then used Co(NO 3 ) 2 as a catalyst precursor,
H3PO 4 as a P source, and heat-treated at 800° C for 1 h. After 12 h of treatment
using a 1 M HCl solution, Co was removed from the sample, and its P doping
amount was 1.84%. They compared the ORR performance of the samples before
and after the removal of Co, and found that although the pure non-metallic P-doped
carbon powder had a much improved ORR performance with the undoped carbon
powder, the ORR performance of the P-doped carbon powder with Co has been
greatly improved compared with non-metallic P-doped carbon powder, indicating
that Co plays an important role in it, as shown in Fig. 4.36. In the process of preparing
P-doped carbon powder with Co as a catalyst, P will combine with Co to form a Co-P
Y. Li et al.
them achieved a kinetic current density of 99 A cm
−3 at 0.8 V by volume, and the
best data previously reported was 2.7 A cm
−3 , which is very close to the 2010 target
(130 A cm
−3 ) set by DOE.
Another breakthrough work was obtained by Wu et al. [217] in 2011. They
mixed carbon powder with large specific surface area, PANI-FeCo-C, transition metal
precursor (cobalt nitrate or ferric chloride), and short-chain aniline oligomer, and then
added (NH 4 ) 2 S 2 O 8 as an oxidant to completely polymerize the aniline. After polymerization, heat treatment was performed in a nitrogen atmosphere, and the obtained
sample was treated in a 0.5 M H 2 SO 4 solution at about 80 °C to remove unstable
metals. Full-cell performance tests show that the ORR performance of PANI-FeCoC as a non-noble metal catalyst is comparable to Pt/C. The H 2 /O 2 battery using
PANI-FeCo-C as the cathode catalyst runs at 0.4 V for 700 h, and there is almost no
degradation in performance. At different voltages, when PANI-FeCo-C is characterized by a rotating disk electrode method, its ORR performance does not substantially
decrease after 9,000 cycles, and in full-cell characterization, its current density after
30,000 cycles also rarely decrease.
In general, these compounds with catalytic activity must meet the following four
conditions: (1) contains a transition metal, mainly Fe, Co, Ni; (2) the source of N
can be a metal precursor compounds, N groups on the surface of the modified carbon
support, or nitrogen-containing gas in the reactor; (3) the source of carbon is the
macrocyclic compound and the support carbon; (4) generally at a high temperature
of 800 °C or higher. Although the treatment temperature is low and the catalyst has
high catalytic activity, it cannot maintain stability.
4.4.3.2 Me-P–C (M = Fe, Co, Ni) Based Catalyst
P and N are elements of the V A group, which have the same outer electrons and
similar chemical properties. Compared with N, P has a larger atomic radius and lower
electronegativity. Density functional theory (DFT) calculations show that when P is
doped into single-walled carbon nanotubes (SWCNTs), P can change the electron
transport properties of SWCNTs and show stronger adsorption capacity for acceptor
molecules(O 2 , etc.) [217, 218]. However, compared with the extensive research of
Me-N–C system, the research of Me-P–C-based catalysts is still in its infancy.
Wu et al. [219] first prepared carbon powder by hydrothermally hydrothermal
method using sucrose as a raw material, then used Co(NO 3 ) 2 as a catalyst precursor,
H3PO 4 as a P source, and heat-treated at 800° C for 1 h. After 12 h of treatment
using a 1 M HCl solution, Co was removed from the sample, and its P doping
amount was 1.84%. They compared the ORR performance of the samples before
and after the removal of Co, and found that although the pure non-metallic P-doped
carbon powder had a much improved ORR performance with the undoped carbon
powder, the ORR performance of the P-doped carbon powder with Co has been
greatly improved compared with non-metallic P-doped carbon powder, indicating
that Co plays an important role in it, as shown in Fig. 4.36. In the process of preparing
P-doped carbon powder with Co as a catalyst, P will combine with Co to form a Co-P