Pt-like Hydrogen Evolution Electrocatalysis on PANI/CoP Hybrid Nanowires by Weakening the Shackles of Hydrogen Ions on the Surfaces of Catalysts Jin-Xian Feng, Si-Yao Tong, Ye-Xiang Tong, and Gao-Ren Li * MOE Laboratory of Bioinorganic and Synthetic Chemistry, The Key Lab of Low-carbon Chemistry & Energy Conservation of Guangdong Province, School of Chemistry, Sun Yat-sen University, Guangzhou 5275, China Zhixin High School, Guangzhou 5080, China E-mail: ligaoren@mail.sysu.edu.cn Scheme S1. The fabrication process of PANI/CoP HNWs-CFs electrocatalysts. 1
Figure S1. SEM image of CFs. Figure S2. (a) SEM image of Co(OH)2 NWs-CFs; (b) TEM image of a Co(OH)2 NW. 2
Figure S3. SEM image CoP NWs-CFs (Inset: TEM image of a CoP NW). 3
a Absorbance/a.u. C-C PANI/CoP HNWs-CFs 1492 para-substituted N-H 3249 3180 C-H 3024 C=C 1572 1429 Benzene rings vibrations Parasubstituted C-N 1279 1346 1188 1140 1394 N=Q=N rings vibrations b Intensity/a.u. Co 2p 3/2 782.34 778.63 Sat. Co 2p Co 2p 1/2 798.32 Sat. 793.50 Co 2+ in CoPO x Co in CoP 3600 3400 30 30001650 1500 1350 10 775 780 785 790 795 800 805 8 Wavenumber/cm -1 Binding energy/ev c Intensity/a.u. PANI/CoP HNWs-CFs P in CoP P 2p 3/2 129.42 130.27 P 2p 1/2 130.75 P 2p P in surface CoPO x d Intensity/a.u. -NH- 399.76 -N= 400.47 -N + - 402.40 N 1s PANI/CoP HNWs-CFs 128 129 130 131 132 133 134 135 136 137 Binding energy/ev 398 399 400 401 402 403 404 Binding energy/ev Figure S4. (a) FT-IR spectra of PANI/CoP HNWs-CFs; (b-d) XPS spectra of (b) Co 2p, (c) P 2p and (d) N 1s of PANI/CoP HNWs-CFs. 4
Figure S5. SEM image of PANI NDs-CFs. (a) Current density/ma cm -2 0 CoP NWs-CFs PANI/CoP=0.25 PANI/CoP=0. - PANI/CoP=0.15 PANI/CoP=0. -40 PANI/CoP=0.05-60 -80-0 -0.30-0.25-0. -0.15-0. -0.05 0.00 Potential/V vs. RHE (b) 24 j a -j c /ma cm -2 5 21 18 15 12 9 6 3 PANI/CoP=0.05 PANI/CoP=0. PANI/CoP=0.15 PANI/CoP=0. PANI/CoP=0.25 0 0 40 60 80 0 Scan rate/mv s -1 Figure S6. (a) HER polarization curves of PANI/CoP HNWs-CFs with different PANI/CoP mass ratios; (b) Charging current density differences j a -j c plotted against the scan rates of PANI/CoP HNWs-CFs with different mass ratios of PANI/CoP.
Current density/ma cm -2 0 - -40-60 -80 0.50 mg cm -2 0.60 mg cm -2 0.70 mg cm -2 0.80 mg cm -2 0.90 mg cm -2 1.00 mg cm -2-0 -0.30-0.25-0. -0.15-0. -0.05 0.00 Potential/V vs. RHE Figure S7. Relationship between the catalytic activity and loading mass of PANI/CoP HNWs-CFs. Current density/a g -1 0 0.4 mg cm -2 PANI NDs - -40-60 -80 0.696 mg cm -2 0.80 mg cm -2 CoP NWs PANI/CoP HNWs -0-0. -0.15-0. -0.05 0.00 Potential/V vs. RHE Figure S8. HER polarization curves of PANI NDs-CFs, CoP NWs-CFs and PANI/CoP HNWs-CFs based on loading masses. 6
0.16 PANI/CoP HNWs-CFs CoP NWs-CFs Overpotential/V 0.12 0.08 0.04 111.8 mv/dec 46.3 mv/dec 0.8 1.0 1.2 1.4 1.6 Log(j/mA.cm -2 ) Figure S9. Tafel plots of PANI/CoP HNWs-CFs and CoP NWs-CFs. j a -j c /ma cm -2 24 21 18 15 12 9 6 3 PANI/CoP HNWs-CFs PANI NDs-CFs CoP NWs-CFs 113.4 mf cm -2 98.34 mf cm -2 19.09 mf cm -2 0 0 40 60 80 0 Scan rate/mv s -1 Figure S. Charging current density differences j a -j c plotted against the scan rates of PANI NDs-CFs, CoP NWs-CFs and PANI/CoP HNWs-CFs electrocatalysts. 7
Figure S11. SEM image of PANI/CoP HNWs-CFs after HER at -0.12 V for 30 h (Inset: TEM image of CoP NW). After HER electrocatalysis Before HER electrocatalysis Potonated N=Q=N Intensity/a.u. -OH -NH + 2 Benzene rings vibrations H 2 O C-C C-N + C=C 3600 3450 3300 3150 3000 1600 1400 10 00 Wavenumber/cm -1 Figure S12. FT-IR spectra of PANI/CoP HNWs-CFs before and after HER at -0.12 V for 30 h. 8
Intensity/a.u. Amorphous PANI * (011) (111) (2) * * * (112) (211) Before 30 h HER After 30 h HER (301) * * * * PANI * CoP 25 30 35 40 45 50 55 60 65 2θ/degree Figure S13. XRD patterns of PANI/CoP HNWs-CFs after HER at -0.12 V for 30 h. 9
a b Figure S14. Hydride proton H 13 O 6 + (a) and (b) Protonated PANI model.
a b c d Figure S15. Models of (a) CoP-H 13 O 6 + ; (b) CoP-H + +6H 2 O; (c) CoP/PANI-H + +6H 2 O; and (d) CoP-H + / PANI+6H 2 O. 11
a b c Figure S16. Simplified CoP cluster: (a) front view (b) top view, and (c) side view. Figure S17. Simplified PANI cluster. 12
a b Figure S18. Simplified PANI/CoP cluster (a) front view and (b) side view. Current density/ma cm -2 0 CoP NWs-CFs (1.0 M PBS ph=7) - -40-60 -80 PANI/CoP HNWs-CFs (1.0 M PBS ph=7) CoP NWs-CFs (0.5 M H 2 SO 4 ) PANI/CoP HNWs-CFs (0.5 M H 2 SO 4 ) -0-0.30-0.25-0. -0.15-0. -0.05 0.00 Potential/V vs. RHE Figure S19. Polarization curves of CoP NWs-CFs and PANI/CoP HNWs-CFs electrocatalysts in ph=7 media (1.0 M PBS) and 0.5 M H 2 SO 4. 13
Table S1. Comparisons of the electrocatalytic activity of PANI/CoP HNWs-CFs catalysts in acidic media vis-à-vis some representative solid-state HER catalysts recently reported. (U: Onset potential; η j : Overpotential at the applied current density; j: Current density). Electrocatalyst PANI/CoP HNWs-CFs Loading/mg cm -2 U/mV η j /mv j/ma.cm -2 Reference 0.80 15 CoP/CC 0.92 38 57 82 1 122 67 0 4 50 0 0 Our work Ref 1 CoP NPs/Ti 2.0 30 85 Ref 2 CoP NSs/Ti 2.0 40 90 146 0 Ref 3 Urchin-like CoP NCs 0.28 50 1 150 180 50 0 Ref 4 0 MoP S 1.0 25 1 50 Ref 5 140 0 CoP@NC 0.3 21 78 115 50 Ref 6 FeP NA/Ti 3.2 16 55 127 0 Ref 7 Co 2 P@NPG 0.5 45 5 194 Ref 8 Cu 3 P NW/CF 15.2 62 143 2 50 Ref 9 84 2 MoP-CA2 0.36 40 125 Ref 0 0 14
Ni 5 P 4 films -- 50 140 150 Ref 11 Nanostructured Ni 2 P 1 50 130 180 0 Ref 12 CoS 2 /RGO-CNT film 1.15 0 142 153 178 0 Ref 13 CoNi@NC 0.62 30 160 224 5 Ref 14 WS 2 /WO 2.9 /C 0.12 115 175 Ref 15 137 CoSe 2 nanoparticles 2.8 75 150 Ref 16 180 0 Defect-rich MoS 2 ultrathin nanosheets 0.285 1 0 215 270 50 Ref 17 Fe 0.9 Co 0.1 S 2 /CNT 4.9 0 1 170 0 Ref 18 MoS 2 /CoSe 2 0.24 11 68 40 40 Ref 19 Core-shell NiAu/Au -- 0 183 2 Ref α-ins ultrathin nanosheets 0.254 80 0 140 Ref 21 MoP@RGO 0.28 118 125 50 Ref 22 WO 2.9 0.285 50 70 94 Ref 23 CoMoS 3 0.114 0 175 2 Ref 24 Pt-TaS 2 0. 0 15 180 190 5 Ref 25
190 Co 9 S 8 @MoS 2 /CNFs 0.212 64 2 Ref 26 250 30 Ni-doped graphene -- 30 162 185 15 Ref 27 60.9 Ni-C-N nanosheets 0.2 34.7 0 50 Ref 28 125 0 138 Co-C-N complex 4.9 0 160 Ref 29 212 0 WO 2 -carbon 138 mesoporous 0.35 0 160 Ref 30 nanowires 212 0 Pt@CIAC-121 -- 300 480 600 Ref 31 16
Table S2. Comparisons of the long-term stability of the PANI/CoP HNWs-CFs catalysts under the acidic conditions vis-à-vis some representative solid-state HER catalysts recently reported. η o : Applied overpotential; j i : initial current density; j f : final constant current density. Electrocatalyst Loading/ mg cm -2 Reaction time/h Electrochemical performance j i =19.2 ma/cm 2 η 0 =50 mv j f =18.8 ma/cm 2 Reference PANI/CoP HNWs-CFs 0.80 30 η 0 =75 mv η 0 =0 mv j i =32.0 ma/cm 2 j f =31.0 ma/cm 2 j i =53.1 ma/cm 2 j f =52.9 ma/cm 2 Our work η 0 =1 mv j i =87.9 ma/cm 2 j f =86.4 ma/cm 2 CoP NSs/Ti 2.0 2.8 η 0 =150 mv j i =1 ma/cm 2 j f =1 ma/cm 2 Ref 3 Urchin-like CoP NCs 0.28 9 η 0 =150 mv j i =1 ma/cm 2 j f =1 ma/cm 2 Ref 4 Cu 3 P NW/CF 15.8 25 η 0 =0 mv j i =28mA/cm 2 j f =28 ma/cm 2 Ref 9 Co 2 P@NPG 0.5 30 η 0 =0 mv η 0 =150 mv j i =6.3 ma/cm 2 j f =6 ma/cm 2 j i =25 ma/cm 2 j f =23 ma/cm 2 Ref 8 MoP-CA2 0.36 24 η 0 =150 mv WS 2 /WO 2.9 /C 0.12 22 η 0 =1 mv j i =27 ma/cm 2 j f =25 ma/cm 2 Ref j i =11 ma/cm 2 j f = ma/cm 2 Ref 15 CoSe 2 nanoparticles 2.8 30 η 0 =155 mv η 0 =173 mv j i = ma/cm 2 j f = ma/cm 2 j i =50 ma/cm 2 Ref 16 17
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