Charge transport in polymeric graphitic carbon nitrides is shown to proceed via diffusive hopping of electron and hole polarons with reasonably high mobilities >10(-5) cm(2) V(-1) s(-1). The power-law behavior of the ultrafast luminescence decay exhibits that the predominant transport direction is perpendicular to the graphitic polymer sheets, thus complementing 2D materials like graphene.

Golden electrons: Visible light excites conduction electron transfer from gold particles to support vacancies where they are taken up by protons to produce hydrogen. This transfer process was visualized by in situ EPR spectroscopy.

The activity of plasmonic Au−TiO 2 catalysts for solar hydrogen production from H 2 O/MeOH mixtures was found to depend strongly on the support phase (anatase, rutile, brookite, or composites thereof) as well as on specific structural properties caused by the method of Au deposition (sol-immobilization, photodeposition, or deposition−precipitation). Structural and electronic rationale have been identified for this behavior. Using a combination of spectroscopic in situ techniques (EPR, XANES, and UV−vis spectroscopy), the formation of plasmonic Au particles from precursor species was monitored, and the chargecarrier separation and stabilization under photocatalytic conditions was explored in relation to H 2 evolution rates. By in situ EPR spectroscopy, it was directly shown that abundant surface vacancies and surface OH groups enhance the stabilization of separated electrons and holes, whereas the enrichment of Ti 3+ in the support lattice hampers an efficient electron transport. Under the given experimental conditions, these properties were most efficiently generated by depositing gold particles on anatase/rutile composites using the deposition−precipitation technique.

Solar light harvesting by photocatalytic H evolution from water could solve the problem of greenhouse gas emission from fossil fuels with alternative clean energy. However, the development of more efficient and robust catalytic systems remains a great challenge for the technological use on a large scale. Here we report the synthesis of a sol-gel prepared mesoporous graphitic carbon nitride (sg-CN) combined with nickel phosphide (Ni P) which acts as a superior co-catalyst for efficient photocatalytic H evolution by visible light. This integrated system shows a much higher catalytic activity than the physical mixture of Ni P and sg-CN or metallic nickel on sg-CN under similar conditions. Time-resolved photoluminescence and electron paramagnetic resonance (EPR) spectroscopic studies revealed that the enhanced carrier transfer at the Ni P-sg-CN heterojunction is the prime source for improved activity.