File Name : figure s1.tif Caption : figure s1. digital photography of ni3s2@feooh/nf with a large size File Name : figure s2.tif Caption : figure s2. low- and high-magnification sem images of ni3s2/nf File Name : figure s3.tif Caption : figure s3. sem and corresponding edx elemental mapping images of ni3s2@feooh/nf File Name : figure s4.tif Caption : figure s4. survey spectrum and high-resolution xps spectrum for ni3s2/nf and ni3s2@feooh/nf File Name : figure s5.tif Caption : figure s5. lsv curves of ni3s2/nf and ni3s2@feooh/nf, ruo2/nf, and nf in 1 m koh (with 90%ir correction). (a) 1 m koh. (b) 1 m koh + 0.5 m nacl File Name : figure s6.tif Caption : figure s6. comparison of the overpotential and stability of ni3s2/nf and ni3s2@feooh/nf in 1 m koh + seawater at 1000 ma cm−2 File Name : figure s7.tif Caption : figure s7. cv curves for (a) ni3s2/nf, (b) ni3s2@feooh/nf at different scan rates increasing from 10 to 100 mv s–1 in alkaline seawater. oxidation peak current versus the scan rate plot for (c) ni3s2/nf, (d) ni3s2@feooh/nf, (e) tof plot File Name : figure s8.tif Caption : figure s8. bode plots corresponding to nyquist plots for (a) ni3s2/nf and (b) ni3s2@feooh/nf. File Name : figure s9.tif Caption : figure s9. cv curves for (a) ni3s2/nf, (b) ni3s2@feooh/nf in the double layer region at different scan rates of 10, 20, 40, 60, 80, 100, 120, and 140 mv s−1 in 1 m koh + seawater File Name : figure s10.tif Caption : figure s10. lsv curves normalized by electrochemical active surface area for ni3s2/nf and ni3s2@feooh/nf in 1 m koh + seawater File Name : figure s11.tif Caption : figure s11. multistep chronopotentiometric curves of ni3s2/nf and ni3s2@feooh/nf without ir-correction File Name : figure s12.tif Caption : figure s12. corrosion polarization curves of ni3s2/nf and ni3s2@feooh/nf in 1 m koh + seawater File Name : figure s13.tif Caption : figure s13. (a) uv-vis absorption spectra of various active chlorine concentrations and (b) the corresponding linear fit File Name : figure s14.tif Caption : figure s14. sem images of ni3s2@feooh/nf after stability at 1000 ma cm−2 (a-c) and 2000 ma cm−2 (d-f) in 1 m koh + seawater. File Name : figure s15.tif Caption : figure s15. xrd patterns of ni3s2@feooh/nf before and after the stability test in 1 m koh + seawater. File Name : figure s16.tif Caption : figure s16. (a) survey spectrum of xps for ni3s2@feooh/nf after the stability test. xps spectra of ni3s2@feooh/nf in the (b) ni 2p, (c) fe 2p, (d) o 1s, and (e) s 2p regions after the stability test File Name : figure s17.tif Caption : figure s17. in situ xrd spectra of ni3s2@feooh/nf File Name : figure s18.tif Caption : figure s18. possible clor pathways of (a) so42⁻-nifeooh and (b) so42⁻-niooh File Name : figure s19.tif Caption : figure s19. possible aem-based pathways of (a) so42⁻-nifeooh and (b) so42⁻-niooh File Name : figure s20.tif Caption : figure s20. sem image of ni3s2@feooh/nf after long-term flow cell operation File Name : figure s21.tif Caption : figure s21. collection of oxygen evolved from seawater oxidation at the j of 1000 ma cm−2 by water drainage method