110
Y. Li et al.
0.8 V (vs. RHE), the specific activity of the 8 nm Pt nanocubes was more than twice
the commercial Pt/C spherical nanoparticles. In addition, the morphology of the Pt
nanocube did not change after the ORR performance test.
Liang et al. [181] first synthesized ultra-fine Te nanowires with large length–
diameter ratio [182], and then used ultra-fine Te nanowires as templates, and coated
the outer layer with carbon to form Te@C nanocables by hydrothermal method.
Then, a Pt nanowire (Pt NW@C) is formed by a substitution reaction between Te
and PtCl 6
2− . Finally, the outer carbon is removed at 400° C for one hour to obtain
the final Pt NW. In 0.5 M H 2 SO 4 , the specific activity of Pt NW at 0.85 V (vs.
RHE) was 2.1 and 1.8 times that of Pt/C and Pt black, respectively. In addition, the
Tafel curve corrected by the diffusion current shows that Pt NW has the highest
kinetic current density in all voltage ranges. They believe that the ORR performance
improvement of Pt nanowires to Pt comes from (1) one-dimensional nanostructures
that are more inclined to expose specific crystal planes; (2) this nanowire structure
has fewer defects; (3) the network structure of one-dimensional nanowires facilitates
the transport of electrons and the diffusion of gases on the electrodes [183, 184].
Koenigsmann et al. [185] placed 2.5 mL of chloroplatinic acid (H 2 PtCl 6 ·xH 2 O, >
99.9%, 10.0 mM) in 20 mL of dimethylformamide, 12.5 mL of toluene, and 2.5 mL of
triethylamine. During the stirring process, 20 mg of sodium borohydride was added,
and the reaction was performed for 3 h, finally the Pt nanowires were obtained. The
average diameter of Pt nanowires is 1.8 ± 0.3 nm and the length is 100 ± 25 nm.
After pickling, the diameter can be further reduced to 1.3 ± 0.4 nm, as shown in
Fig. 4.17. The Pt nanowires they prepared have a more positively ORR curve. At
0.9 V (vs. RHE), their specific activity reached 1.45 mA cm
−2 , which is 7 times that
of commercial Pt/C catalysts (0.21 mA cm
−2 ).
Although Pt catalysts with special nanostructures have greatly improved their
ORR performance due to their nano-effects and structural effects, especially these
special nano-structures greatly increase the stability of Pt. But they cannot fundamentally change the electronic structure of Pt, so that ORR activity can be greatly
improved. An effective way is to introduce a second transition metal while forming
a special nanostructure of Pt to form a PtM alloy with a special nanostructure. Xiaoqing Huang et al. [186] designed a new control method to prepare a high specific
surface area Pt–Co nanowire with a zigzag structure, and its surface has a higher
density of high index crystal plane, as shown in Fig. 4.18. The evaluation results of
its oxygen reduction reaction catalysis data show that the mass activity of the zigzag
Pt–Co nanowires for oxygen reduction catalysis reaches nearly 4 A/mg @ 0.9 V,
which is 33 times that of commercial Pt/C. Theoretical calculations show that the
high ORR activity on PtCo nanowires is mainly derived from [158] and the Empty
site of high index crystal plane [310] on the nanowire surface [186].
Wu et al. [165] used Pt(acac) 2 as the precursor of Pt, and used Ni(acac) 2 , HAuCl 4 ,
and Pd(acac) 2 as the precursors of the second added metal, respectively. In the mixed
solution of oleylamine, oleic acid, and diphenyl ether, Pt–M (M = Au, Ni and Pd)
icosahedral nanocrystals were synthesized by filling a certain flow of CO gas during
the heating reduction process. The size of the synthesized Pt 3 Ni icosahedrons is 13
± 0.3 nm, as shown in Fig. 4.19. The HRTEM image shows a five-fold symmetrical
Y. Li et al.
0.8 V (vs. RHE), the specific activity of the 8 nm Pt nanocubes was more than twice
the commercial Pt/C spherical nanoparticles. In addition, the morphology of the Pt
nanocube did not change after the ORR performance test.
Liang et al. [181] first synthesized ultra-fine Te nanowires with large length–
diameter ratio [182], and then used ultra-fine Te nanowires as templates, and coated
the outer layer with carbon to form Te@C nanocables by hydrothermal method.
Then, a Pt nanowire (Pt NW@C) is formed by a substitution reaction between Te
and PtCl 6
2− . Finally, the outer carbon is removed at 400° C for one hour to obtain
the final Pt NW. In 0.5 M H 2 SO 4 , the specific activity of Pt NW at 0.85 V (vs.
RHE) was 2.1 and 1.8 times that of Pt/C and Pt black, respectively. In addition, the
Tafel curve corrected by the diffusion current shows that Pt NW has the highest
kinetic current density in all voltage ranges. They believe that the ORR performance
improvement of Pt nanowires to Pt comes from (1) one-dimensional nanostructures
that are more inclined to expose specific crystal planes; (2) this nanowire structure
has fewer defects; (3) the network structure of one-dimensional nanowires facilitates
the transport of electrons and the diffusion of gases on the electrodes [183, 184].
Koenigsmann et al. [185] placed 2.5 mL of chloroplatinic acid (H 2 PtCl 6 ·xH 2 O, >
99.9%, 10.0 mM) in 20 mL of dimethylformamide, 12.5 mL of toluene, and 2.5 mL of
triethylamine. During the stirring process, 20 mg of sodium borohydride was added,
and the reaction was performed for 3 h, finally the Pt nanowires were obtained. The
average diameter of Pt nanowires is 1.8 ± 0.3 nm and the length is 100 ± 25 nm.
After pickling, the diameter can be further reduced to 1.3 ± 0.4 nm, as shown in
Fig. 4.17. The Pt nanowires they prepared have a more positively ORR curve. At
0.9 V (vs. RHE), their specific activity reached 1.45 mA cm
−2 , which is 7 times that
of commercial Pt/C catalysts (0.21 mA cm
−2 ).
Although Pt catalysts with special nanostructures have greatly improved their
ORR performance due to their nano-effects and structural effects, especially these
special nano-structures greatly increase the stability of Pt. But they cannot fundamentally change the electronic structure of Pt, so that ORR activity can be greatly
improved. An effective way is to introduce a second transition metal while forming
a special nanostructure of Pt to form a PtM alloy with a special nanostructure. Xiaoqing Huang et al. [186] designed a new control method to prepare a high specific
surface area Pt–Co nanowire with a zigzag structure, and its surface has a higher
density of high index crystal plane, as shown in Fig. 4.18. The evaluation results of
its oxygen reduction reaction catalysis data show that the mass activity of the zigzag
Pt–Co nanowires for oxygen reduction catalysis reaches nearly 4 A/mg @ 0.9 V,
which is 33 times that of commercial Pt/C. Theoretical calculations show that the
high ORR activity on PtCo nanowires is mainly derived from [158] and the Empty
site of high index crystal plane [310] on the nanowire surface [186].
Wu et al. [165] used Pt(acac) 2 as the precursor of Pt, and used Ni(acac) 2 , HAuCl 4 ,
and Pd(acac) 2 as the precursors of the second added metal, respectively. In the mixed
solution of oleylamine, oleic acid, and diphenyl ether, Pt–M (M = Au, Ni and Pd)
icosahedral nanocrystals were synthesized by filling a certain flow of CO gas during
the heating reduction process. The size of the synthesized Pt 3 Ni icosahedrons is 13
± 0.3 nm, as shown in Fig. 4.19. The HRTEM image shows a five-fold symmetrical