Photoelectrochemical (PEC) reduction of CO with HO not only provides an opportunity for reducing net CO emissions but also produces value-added chemical feedstocks and fuels. Syngas, a mixture of CO and H, is a key feedstock for the production of methanol and other commodity hydrocarbons in industry. However, it is challenging to achieve efficient and stable PEC CO reduction into syngas with controlled composition owing to the difficulties associated with the chemical inertness of CO and complex reaction network of CO conversion. Herein, by employing a metal/oxide interface to spontaneously activate CO molecule and stabilize the key reaction intermediates, we report a benchmarking solar-to-syngas efficiency of 0.87% and a high turnover number of 24 800, as well as a desirable high stability of 10 h. Moreover, the CO/H ratios in the composition can be tuned in a wide range between 4:1 and 1:6 with a total unity Faradaic efficiency. On the basis of experimental measurements and theoretical calculations, we present that the metal/oxide interface provides multifunctional catalytic sites with complementary chemical properties for CO activation and conversion, leading to a unique pathway that is inaccessible with the individual components. The present approach opens new opportunities to rationally develop high-performance PEC systems for selective CO reduction into valuable carbon-based chemicals and fuels.

The combination of earth-abundant catalysts and semiconductors, for example, molybdenum sulfides and planar silicon, presents a promising avenue for the large-scale conversion of solar energy to hydrogen. The inferior interface between molybdenum sulfides and planar silicon, however, severely suppresses charge carrier extraction, thus limiting the performance. Here, we demonstrate that defect-free gallium nitride nanowire is ideally used as a linker of planar silicon and molybdenum sulfides to produce a high-quality shell-core heterostructure. Theoretical calculations revealed that the unique electronic interaction and the excellent geometric-matching structure between gallium nitride and molybdenum sulfides enabled an ideal electron-migration channel for high charge carrier extraction efficiency, leading to outstanding performance. A benchmarking current density of 40 ± 1 mA cm−2 at 0 V vs. reversible hydrogen electrode, the highest value ever reported for a planar silicon electrode without noble metals, and a large onset potential of +0.4 V were achieved under standard one-sun illumination.

A unique GaN:Sn nanoarchitecture is integrated on planar silicon to demonstrate an energetically favorable reaction path for aqueous photoelectrochemical CO2 reduction towards formic acid with high efficiency at low overpotential.

Summary Photoelectrochemical CO 2 reduction into syngas (a mixture of CO and H 2 ) provides a promising route to mitigate greenhouse gas emissions and store intermittent solar energy into value-added chemicals. Design of photoelectrode with high energy conversion efficiency and controllable syngas composition is of central importance but remains challenging. Herein, we report a decoupling strategy using dual cocatalysts to tackle the challenge based on joint computational and experimental investigations. Density functional theory calculations indicate the optimization of syngas generation using a combination of fundamentally distinctive catalytic sites. Experimentally, by integrating spatially separated dual cocatalysts of a CO-generating catalyst and a H 2 -generating catalyst with GaN nanowires on planar Si photocathode, we report a record high applied bias photon-to-current efficiency of 1.88% and controllable syngas products with tunable CO/H 2 ratios (0–10) under one-sun illumination. Moreover, unassisted solar CO 2 reduction with a solar-to-syngas efficiency of 0.63% is demonstrated in a tandem photoelectrochemical cell.

Molecular doping has emerged as a powerful strategy to tune the charge transport properties of organic field-effect transistors (OFETs). However, the limited tool-box of molecular dopants and unresolved challenges of stability, uniformity of the doping, and matching the energy levels constrain the achieved OFET device performance and thwart the practical applications. Here, nitrofluorene (NF) acceptors are introduced as effective p-dopants in polymer OFETs, resulting in outstanding device performance of a standard commercial diketopyrrolopyrrole-thienothiophene (DPP-DTT) polymer. An ∼5-fold enhancement in the saturation field-effect mobility (up to ∼8 cm2 V–1 s–1) is realized in ambient air operations after doping with 2,4,5,7-tetranitrofluorenone. Importantly, the achieved effective mobility (which accounts for device nonideality) exceeds 6 cm2 V–1 s–1, which is among the highest values reported for polymer OFETs. The spectroscopic, microscopic, X-ray diffraction, and electrical investigations elucidate the role of NF dopants in mitigating charge carrier traps, lowering the contact resistance, and maximizing the structural order of the polymer films. Energetic disorder reduces significantly upon doping as revealed via variable temperature mobility measurements.