Shape-Dependent Performance of Cu/Cu2 O for Photocatalytic Reduction of CO2.

The photocatalytic conversion of CO2 into solar fuels or chemicals is a sustainable approach to relieve the immediate problems related to global warming and the energy crisis. This study concerns the effects of morphological control on a Cu/Cu2 O-based photocatalyst for CO2 reduction. The as-synthesized spherical Cu/Cu2 O photocatalyst exhibits higher activity than the octahedral one under visible light irradiation. The difference in photocatalytic performance between these two catalysts could be attributed to the following two factors: (1) The multifaceted structure of spherical Cu/Cu2 O favors charge separation; (2) octahedral Cu/Cu2 O only contains more positively charged (111) facets, which are unfavorable for CO2 photoreduction. The results further highlight the importance of utilizing crystal facet engineering to further improve the performance of CO2 reduction photocatalysts.

A "uniform" heterogeneous photocatalyst: integrated p-n type CuInS2/NaInS2 nanosheets by partial ion exchange reaction for efficient H2 evolution.

Single-crystalline-like P-N type CuInS2/NaInS2 heterogeneous nanosheets were synthesized by partial cation exchange reaction and show highly improved photocatalytic H2 evolution activity attributed to the increased efficiency of interfacial charge transfer.

Enhancement in hydrogen evolution using Au-TiO2 hollow spheres with microbial devices modified with conjugated oligoelectrolytes.

OBJECTIVE: Although photoelectrochemical (PEC) water splitting heralds the emergence of the hydrogen economy, the need for external bias and low efficiency stymies the widespread application of this technology. By coupling water splitting (in a PEC cell) to a microbial fuel cell (MFC) using Escherichia coli as the biocatalyst, this work aims to successfully demonstrate a sustainable hybrid PEC-MFC platform functioning solely by biocatalysis and solar energy, at zero bias. Through further chemical modification of the photo-anode (in the PEC cell) and biofilm (in the MFC), the performance of the hybrid system is expected to improve in terms of the photocurrent generated and hydrogen evolved. METHODS: The hybrid system constitutes the interconnected PEC cell with the MFC. Both PEC cell and MFC are typical two-chambered systems housing the anode and cathode. Au-TiO2 hollow spheres and conjugated oligoelectrolytes were synthesised chemically and introduced to the PEC cell and MFC, respectively. Hydrogen evolution measurements were performed in triplicates. RESULTS: The hybrid PEC-MFC platform generated a photocurrent density of 0.35 mA/cm2 (~70× enhancement) as compared with the stand-alone P25 standard PEC cell (0.005 mA/cm2) under one-sun illumination (100 mW/cm2) at zero bias (0 V vs. Pt). This increase in photocurrent density was accompanied by continuous H2 production. No H2 was observed in the P25 standard PEC cell whereas H2 evolution rate was ~3.4 µmol/h in the hybrid system. The remarkable performance is attributed to the chemical modification of E. coli through the incorporation of novel conjugated oligoelectrolytes in the MFC as well as the lower recombination rate and higher photoabsorption capabilities in the Au-TiO2 hollow spheres electrode. CONCLUSIONS: The combined strategy of photo-anode modification in PEC cells and chemically modified MFCs shows great promise for future exploitation of such synergistic effects between MFCs and semiconductor-based PEC water splitting.

Ion-induced synthesis of uniform single-crystalline sulphide-based quaternary-alloy hexagonal nanorings for highly efficient photocatalytic hydrogen evolution.

Uniform single-crystalline quaternary sulphide nanoring photocatalysts are synthesized via the copper-ion-induced Kirkendall effect and is followed by a cation exchange reaction. The obtained Cu(2+)-doped ZnIn(2)S(4) nanorings show highly preserved morphology, and demonstrate high visible-light-driven photocatalytic activity for H(2) evolution in water splitting.