A Whole-Cell Inorganic-Biohybrid System Integrated by Reduced Graphene Oxide for Boosting Solar Hydrogen Production

Abstract

The photoelectron transfer between semiconductors and cells is the rate-determining step that controls the solar H2 production of whole-cell inorganic-biohybrid systems (IBSs). Herein, we constructed an IBS by using reduced graphene oxide (RGO) to integrate Shewanella oneidensis MR-1 (SW) cells and Cu2O, which exhibited a 11–38-fold enhancement of photocatalytic H2 production compared with RGO-free IBSs (Cu2O/SW and Cu2O/organic electron mediator/SW). Further analysis revealed that RGO provided multifunctional contributions to H2 production from IBS, that is, sufficient area for IBS supporting, efficient photoelectron collection from Cu2O, and effective electron distribution into the cells. This study offers opportunities for rationally designing electron transfer pathways to achieve high-performance IBSs.

Interfacing Iodine‐Doped Hydrothermally Carbonized Carbon with Escherichia coli through an “Add‐on” Mode for Enhanced Light‐Driven Hydrogen Production

“…This finding was consistent with the previous reported Cu 2 O/RGO/Shewanella oneidensis system. [31] Overall, these results suggested that the electron transfer pathway at the interface of I-HTCC and E. coli cells was established and played an important role for the photo-enhanced H 2 production in the biohybrid system.…”

“…As those shown in Figure 2b, the H 2 production was only slightly increased with the simple mixing of I-HTCC and untreated E. coli cells, which was caused by the random electrons diffusion across cell membrane. [31] Therefore, increasing in H 2 production of I-HTCC@E. coli biohybrid system indicated that the close interfacial interactions between I-HTCC and E. coli was essential for the electrons delivery. To confirm the role of photoelectrons in H 2 production, the scavenger study was performed with the supplement of Cr (VI), a strong oxidant, in the biohybrid system.…”

“…The photoelectrons transfer in the biotic-abiotic interface is the rate-determining step for the light-driven H 2 production of PBSs. [31] And the electrons can be directly delivered to bacteria through the redox proteins in the outer membrane or the soluble redox shuttles. [32] Therefore, with this delicate self-assembled biohybrid system, the photo-generated electrons were expected to transfer from I-HTCC to bacterial cell membrane without sluggish kinetics compared to that of in the suspended systems, which mediated by electron transfer agents such as MV.…”

“…[6b] Besides, the well coated I-HTCC might also act as solid-state electron mediators for electron relay within the membrane owing to the good conductivity of I-HTCC. [31] However, the perturbation of injected electrons on the microbial metabolism and S2C conversion is still poorly understood and needed further investigation.…”

“…[15] As the CB of I-HTCC was −0.53 V versus NHE (Figure S2, Supporting Information), theoretically the transfer of photoelectrons to membrane-bounded proteins (MBPs, ≈−0.3-0 V vs NHE) and NADH/NAD + (E = −0.32 V vs NHE) was thermodynamically favored. [31] To prove the direct electron transfer from I-HTCC to cells, different concentrations of ionophores (2,4-DNP) were applied. Ionophores can disrupt electron transfer chain and inhibit the generation of ATP in cells, thus blocking H 2 yield with the consumption of sugar.…”