@article {1081, title = {An In0.42Ga0.58N tunnel junction nanowire photocathode monolithically integrated on a nonplanar Si wafer}, journal = {Nano Energy}, volume = {57}, year = {2019}, pages = {405-413}, abstract = {

Published on March 1st, 2019. Group III-nitride semiconductors exhibit many ideal characteristics for solar water splitting, including a tunable energy bandgap across nearly the entire solar spectrum and suitable band edge positions for water oxidation and proton reduction under visible and near-infrared light irradiation. To date, however, the best reported energy conversion efficiency for III-nitride semiconductor photocathodes is still below 1\%. Here we report on the demonstration of a relatively efficient p-type In0.42Ga0.58N photocathode, which is monolithically integrated on an n-type nonplanar Si wafer through a GaN nanowire tunnel junction. The open pillar design, together with the nonplanar Si wafer can significantly maximize light trapping, whereas the tunnel junction reduces the interfacial resistance and enhances the extraction of photo-generated electrons. In addition, photodeposited Pt nanoparticles on InGaN nanowire surfaces significantly improve the cathodic performance. The nanowire photocathode exhibits a photocurrent density of 12.3 mA cm-2 at 0 V vs. RHE and an onset potential of 0.79 V vs. RHE under AM 1.5 G one-sun illumination. The maximum applied bias photon-to-current efficiency reaches 4\% at ~0.52 V vs. RHE, which is one order of magnitude higher than the previously reported values for III-nitride photocathodes. Significantly, no performance degradation was measured for over 30 h solar water splitting with a steady photocurrent density ~12 mA cm-2 without using any extra surface protection, which is attributed to the spontaneous formation of N-terminated surfaces of InGaN nanowires to protect against photocorrosion.

}, issn = {2211-2855}, doi = {10.1016/j.nanoen.2018.12.067}, url = {http://www.sciencedirect.com/science/article/pii/S2211285518309807}, author = {Yongjie Wang and Srinivas Vanka and Jiseok Gim and Yuanpeng Wu and Ronglei Fan and Yazhou Zhang and Jinwen Shi and Mingrong Shen and Robert Hovden and Zetian Mi} } @article {1093, title = {A Single-Junction Cathodic Approach for Stable Unassisted Solar Water Splitting}, journal = {Joule}, year = {2019}, abstract = {

Published in August 2019.

}, issn = {25424351}, doi = {10.1016/j.joule.2019.07.022}, url = {https://linkinghub.elsevier.com/retrieve/pii/S2542435119303666}, author = {Yongjie Wang and Yuanpeng Wu and Jonathan Schwartz and Suk Hyun Sung and Robert Hovden and Zetian Mi} } @article {1042, title = {Solar Water Oxidation by an InGaN Nanowire Photoanode with a Bandgap of 1.7 eV}, journal = {ACS Energy Letters}, volume = {3}, year = {2018}, note = {

{\textquoteright}doi: 10.1021/acsenergylett.0c01132\n - I.Am.Hydrogen{\textquoteright} {\textquoteright}\n - jyoungstrom{\textquoteright} {\textquoteright}Jason thinks this is great.\n\ \n - jyoungstrom{\textquoteright} {\textquoteright}\n - estechel{\textquoteright}

}, pages = {307-314}, abstract = {

Published on February 9th, 2018. The performance of overall solar water splitting has been largely limited by the half-reaction of water oxidation. Here, we report a 1.7 eV bandgap InGaN nanowire photoanode for efficient solar water oxidation. It produces a low onset potential of 0.1 V versus a reversible hydrogen electrode (RHE) and a high photocurrent density of 5.2 mA/cm2 at a potential as low as 0.6 V versus RHE. The photoanode yields a half-cell solar energy conversion efficiency up to 3.6\%, a record for a single-photon photoanode to our knowledge. Furthermore, in the presence of hole scavengers, the photocurrent density of the InGaN photoanode reaches 21.2 mA/cm2 at 1.23 V versus RHE, which approaches the theoretical limit for a 1.7 eV InGaN absorber. The InGaN nanowire photoanode may serve as an ideal top cell in a photoelectrochemical tandem device when stacked with a 0.9{\textendash}1.2 eV bandgap bottom cell, which can potentially deliver solar-to-hydrogen efficiency over 25\%.

}, doi = {10.1021/acsenergylett.7b01138}, url = {https://doi.org/10.1021/acsenergylett.7b01138}, author = {Sheng Chu and Srinivas Vanka and Yichen Wang and Jiseok Gim and Yongjie Wang and Yong-Ho Ra and Robert Hovden and Hong Guo and Ishiang Shih and Zetian Mi} }