1 Electronic supplementary information (ESI) for A Facile Approach for Preparing Densely-Packed Individual p-NiO/n- Fe 2 O 3 Heterojunction Nanowires for Photoelectrochemical Water Splitting Ashutosh K. Singh a, and Debasish Sarkar* , b , a Large Area Device Laboratory, Centre for Nano and Soft Matter Sciences, Jalahalli, Bengaluru- 560013, India. b Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru-560012, India. __________________________ * Author to whom correspondence should be addressed. E-mail: deb.sarkar1985@gmail.com and debasishs@iisc.ac.in Tel: +91 (080) 2293 2945. Authors contributed equally to this work Electronic Supplementary Material (ESI) for Nanoscale. This journal is © The Royal Society of Chemistry 2018