SiCP₄ Monolayer with a Direct Band Gap and High Carrier Mobility for Photocatalytic Water Splitting

Abstract

Photocatalytic water splitting is a promising method that uses sunlight to generate hydrogen from water to provide clean and renewable energy resources. Two-dimensional materials with abundant active sites are ideal candidates for achieving this goal; however, few of the known ones can meet the rigorous requirement of photocatalytic water splitting. By using first-principles swarm-intelligence search calculations, we have successfully identified two new semiconducting SiCP2 and SiCP4 monolayers. Their band-edge heights evidently straddle the redox potentials of water. For the more prominent SiCP4 monolayer, additional external biases of 0.32 V for water oxidation and 0.03 V for the hydrogen reduction half-reaction would be enough to drive its reaction sequences at pH 0, and it can spontaneously proceed to the water oxidation half-reaction in a neutral solution. Interestingly, the excellent optical absorbance ability (∼104 cm–1) and high carrier mobility (∼105 cm2 V–1 s–1) of SiCP2 and SiCP4 facilitate the utilization of sunlight and the fast transportation of photogenerated carriers. All of these properties make SiCP2 and SiCP4 monolayers promising candidates for applications in photocatalytic water splitting.

Regulating excitonic effects in non-oxide based XPSe3 (X = Cd, Zn) monolayers towards enhanced photocatalysis for overall water splitting

“…The rate-limiting step is the formation of OH* from *, which has a limiting potential of 3.14 V (3.01 V) for CdPSe 3 (ZnPSe 3 ) and is comparable to that of Pd 3 P 2 S 8 , which has a ratelimiting potential of 2.77 V. 83 Incorporating the intrinsic potential of photogenerated holes (U CdPSe 3 h ¼ 1:78 V and U ZnPSe 3 h ¼ 1:70 V), a moderate external bias voltage of 1.36 V and 1.30 V for CdPSe 3 and ZnPSe 3 , respectively, is required to drive the OER. These values are similar to the external bias voltage required for SiCP 2 (0.85 V), 84 and lies in the range of those of many transition metal carbides and oxides (0.49-1.70 V), 85 with the advantage of not using precious metals such as ruthenium and iridium, escaping the bottleneck of scarcity and high cost associated with them. 86 We further studied the HER process, where we note that under dark conditions (U = 0), the formation of H* is endothermic, with a DG of 1.46 V and 1.38 V for CdPSe 3 and ZnPSe 3 , respectively.…”

Unconventional Anisotropy in Excitonic Properties and Carrier Mobility in Iodine-Based XTeI (X = Ga, In) Monolayers for Visible-Light Photocatalytic Water Splitting

“…The formation of OOH* from O* is the ratelimiting step, with a limiting potential of 2.14 V (2.33 V) for GaTeI (InTeI). Therefore, after incorporating the intrinsic potential of photogenerated holes (U h GaTeI = 2.04 V and U h InTeI = 2.30 V), a minimal amount of external bias voltage of 0.10 and 0.03 V for GaTeI and InTeI, respectively, is required to drive the OER which is much lower than that of SiCP 4 76 and PdSeO 3 64 monolayers. Similar to the OER, in the dark condition (U = 0), the formation of H* species is endothermic, with ΔG of 1.92 and 1.98 V for GaTeI and InTeI, respectively.…”

Kagome-like BiP3 Monolayer: An Emerging Quasi-Direct Auxetic Semiconductor Coupled with High Anisotropic Mobility toward Visible-Light-Driven Photoelectrocatalytic pH-Robust Overall Water-Splitting

“…Furthermore, the values of U e and U h change with pH according to the following equations U e = U e pH 0 − 0.059 × pH U h = U h pH 0 + 0.059 × pH In this case, the U e and U h are found to be 1.85 and 3.24 eV for the strain-free BiP 3 monolayer at pH 0, which are several times higher than many other 2D Janus materials. For instance, at pH 0, the values of U e and U h are 0.87 and 1.52 eV for the SiP 2 monolayer, 0.33 and 1.27 eV for the SiCP 2 monolayer, 0.81 and 1.51 eV for the MoSi 2 N 4 monolayer, 1.11 and 2.48 eV for the WSSe monolayer, 0.26 and 1.73 eV for the C 3 S monolayer, and 0.40 and 1.37 eV for the Sn 2 S 2 P 4 monolayer . Moreover, positive values of U e and U h suggest a large driving force for the redox reactions of water, as they favor the transfer of photoexcited carriers, thereby promoting the light-induced process of the water-splitting reaction.…”