Single-Crystal Integrated Photoanodes Based on 4H-SiC Nanohole Arrays for Boosting Photoelectrochemical Water Splitting Activity

Abstract

Photoelectrochemical (PEC) splitting of water into H2 and O2 by direct use of sunlight is an ideal strategy for the production of clean and renewable energy, which fundamentally relies on the exploration of advanced photoanodes with high performance. In the present work, we report that single-crystal integrated photoanodes, that is, 4H-SiC nanohole arrays (active materials) and SiC wafer substrate (current collector), are established into a totally single-crystal configuration without interfaces, which was based on a two-step electrochemical etching process. The as-fabricated SiC photoanode showed a rather low onset potential of −0.016 V vs reversible hydrogen electrode (RHE) and a high photocurrent density of 3.20 mA/cm2 vs RHE 1.23 V, which were both superior to those of all reported SiC ones. Furthermore, such a rationally designed photoanode exhibited a fast photoresponse, wide photoresponse wavelength range, and long-term stability, representing its overall excellent PEC performance.

Superior integrated field emission cathode with ultralow turn‐on field and high stability based on SiC nanocone arrays

“…Three peaks of 4H-SiC are observed in the range of 600-1200 cm −1 , which could be mainly assigned to the longitudinal optical (LO) mode at approximately 968 cm −1 , as well as two transverse optical modes at approximately 775 cm −1 (E 1 , LO) and 793 cm −1 (E 2 , LO), respectively. 20 Both the XRD and Raman spectra results clearly confirm that the electrochemical etching approach has no phase structure effect of the utilized 4H-SiC wafer. 2C, revealing that the tip presents a perfect crystal structure without defects, which favors the tiny tips that are effectively resistant to strong electrostatic forces during the electron process and thus maintain high electron emission stability.…”

“…Figure 1E exhibits the typical Rama spectrum of the etched sample. Three peaks of 4 H ‐SiC are observed in the range of 600–1200 cm −1 , which could be mainly assigned to the longitudinal optical (LO) mode at approximately 968 cm −1 , as well as two transverse optical modes at approximately 775 cm −1 ( E 1 , LO) and 793 cm −1 ( E 2 , LO), respectively 20 . Both the XRD and Raman spectra results clearly confirm that the electrochemical etching approach has no phase structure effect of the utilized 4 H ‐SiC wafer.…”

Nanoarray Structures for Artificial Photosynthesis

“…[85,86] Till date, several attempts have been made to enhance light absorption in various nanoarray structures, and among them the one with the most optimum results are summarized in Figure 2. The introduction of multiple light scattering, [87][88][89][90] antireflection, [91][92][93][94] slow light effect, [95,96] surface plasmon resonance (SPR), [97][98][99] bandgap narrowing, [69,100] and photosensitization, [101][102][103] can increase the light absorption intensity as well as extend the spectral range of the nanoarray structures. Furthermore, the hybrid structures combining more than one light management strategies have successfully achieved synergetic effects in light absorption.…”

Anisotropic Charge Transport Enabling High‐Throughput and High‐Aspect‐Ratio Wet Etching of Silicon Carbide

“…Silicon carbide (SiC) has been widely applied in field emitters, [ 1–3 ] photodetectors, [ 4–6 ] and photoelectrochemical water splitting [ 7–11 ] because of its wide bandgap, high thermal conductivity, and excellent chemical inertness. [ 12 ] Recently, SiC has also been shown as an ideal material for high‐performance power electronic devices, [ 13 ] such as fin field‐effect transistor effect based metal‐oxide‐semiconductor field‐effect transistor [ 14,15 ] and insulated gate bipolar transistors (IGBTs), [ 16,17 ] which are used in high‐speed railways [ 18,19 ] and electric vehicles.…”

“…Silicon carbide (SiC) has been widely applied in field emitters, [1][2][3] photodetectors, [4][5][6] and photoelectrochemical water splitting [7][8][9][10][11] because of its wide bandgap, high thermal conductivity, and excellent chemical inertness. [12] Recently, SiC has also been shown as an ideal material for high-performance power electronic trigger oxidation of SiC and subsequent etching.…”